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What is electricity? Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwell's equations. Various common phenomena are related to electricity, including lightning, static electricity, electric heating, electric discharges and many others. The presence of an electric charge, which can be either positive or negative, produces an electric field. The movement of electric charges is an electric current and produces a magnetic field. When a charge is placed in a location with a non-zero electric field, a force will act on it. The magnitude of this force is given by Coulomb's law. If the charge moves, the electric field would be doing work on the electric charge. Thus we can speak of electric potential at a certain point in space, which is equal to the work done by an external agent in carrying a unit of positive charge from an arbitrarily chosen reference point to that point without any acceleration and is typically measured in volts. Electricity is at the heart of many modern technologies, being used for: - electric power where electric current is used to energise equipment; - electronics which deals with electrical circuits that involve active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies. Electrical phenomena have been studied since antiquity, though progress in theoretical understanding remained slow until the seventeenth and eighteenth centuries. The theory of electromagnetism was developed in the 19th century, and by the end of that century electricity was being put to industrial and residential use by electrical engineers. The rapid expansion in electrical technology at this time transformed industry and society, becoming a driving force for the Second Industrial Revolution. Electricity's extraordinary versatility means it can be put to an almost limitless set of applications which include transport, heating, lighting, communications, and computation. Electrical power is now the backbone of modern industrial society.
What is night? Night or nighttime (also spelled night-time or night time) is the period of ambient darkness from sunset to sunrise during each 24-hour day, when the Sun is below the horizon. The exact time when night begins and ends (equally true with evening) depends on the location and varies throughout the year. When night is considered as a period that follows evening, it is usually considered to start around 8 pm and to last to about 4 am. Night ends with coming of morning at sunrise. The word can be used in a different sense as the time between bedtime and morning. In common communication, the word night is used as a farewell ("good night") and sometimes shortened to "night", mainly when someone is going to sleep or leaving. Complete darkness or astronomical night is the period between astronomical dusk and astronomical dawn when the Sun is between 18 and 90 degrees below the horizon and does not illuminate the sky. As seen from latitudes between about 48.56° and 65.73° north or south of the Equator, complete darkness does not occur around the summer solstice because, although the Sun sets, it is never more than 18° below the horizon at lower culmination, -90° sun a angles occur at Tropic of Cancer on December Solstice and Tropic of Capricorn on June Solstice and at equator on equinoxes. The opposite of night is day (or "daytime", to distinguish it from "day" referring to a 24-hour period). The start and end points of time for a night vary, based on factors such as season and latitude. Twilight is the period of night after sunset or before sunrise when the Sun still illuminates the sky when it is below the horizon. At any given time, one side of Earth is bathed in sunlight (the daytime) while the other side is in the shadow caused by Earth blocking the sunlight. The central part of the shadow is called the umbra. Natural illumination at night is still provided by a combination of moonlight, planetary light, starlight, zodiacal light, gegenschein, and airglow. In some circumstances, aurorae, lightning, and bioluminescence can provide some illumination. The glow provided by artificial lighting is sometimes referred to as light pollution because it can interfere with observational astronomy and ecosystems. - Wikipedia
What is death? Death is the permanent, irreversible cessation of all biological functions that sustain a living organism. Brain death is sometimes used as a legal definition of death. The remains of a previously living organism normally begin to decompose shortly after death. Death is an inevitable, universal process that eventually occurs in all living organisms. Death is generally applied to whole organisms; the similar process seen in individual components of a living organism, such as cells or tissues, is necrosis. Something that is not considered a living organism, such as a virus, can be physically destroyed but is not said to die. As of the early 21st century, over 150,000 humans die each day. Many cultures and religions have the idea of an afterlife, and also hold the idea of judgement of good and bad deeds (Heaven, Hell, Karma). One of the challenges in defining death is in distinguishing it from life. As a point in time, death would seem to refer to the moment at which life ends. Determining when death has occurred is difficult, as cessation of life functions is often not simultaneous across organ systems. Such determination, therefore, requires drawing precise conceptual boundaries between life and death. This is difficult, due to there being little consensus on how to define life. It is possible to define life in terms of consciousness. When consciousness ceases, a living organism can be said to have died. One of the flaws in this approach is that there are many organisms that are alive but probably not conscious (for example, single-celled organisms). Another problem is in defining consciousness, which has many different definitions given by modern scientists, psychologists and philosophers. Additionally, many religious traditions, including Abrahamic and Dharmic traditions, hold that death does not (or may not) entail the end of consciousness. In certain cultures, death is more of a process than a single event. It implies a slow shift from one spiritual state to another. - Wikipedia
What is a frog? A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura (literally without tail in Ancient Greek). The oldest fossil "proto-frog" appeared in the early Triassic of Madagascar, but molecular clock dating suggests their origins may extend further back to the Permian, 265 million years ago. Frogs are widely distributed, ranging from the tropics to subarctic regions, but the greatest concentration of species diversity is in tropical rainforest. There are about 7,300 recorded species, which account for around 88% of extant amphibian species. They are also one of the five most diverse vertebrate orders. Warty frog species tend to be called toads, but the distinction between frogs and toads is informal, not from taxonomy or evolutionary history. An adult frog has a stout body, protruding eyes, anteriorly-attached tongue, limbs folded underneath, and no tail (except in tailed frogs). Frogs have glandular skin, with secretions ranging from distasteful to toxic. Their skin varies in colour from well-camouflaged dappled brown, grey and green to vivid patterns of bright red or yellow and black to show toxicity and ward off predators. Adult frogs live in fresh water and on dry land; some species are adapted for living underground or in trees. Frogs typically lay their eggs in water. The eggs hatch into aquatic larvae called tadpoles that have tails and internal gills. They have highly specialized rasping mouth parts suitable for herbivorous, omnivorous or planktivorous diets. The life cycle is completed when they metamorphose into adults. A few species deposit eggs on land or bypass the tadpole stage. Adult frogs generally have a carnivorous diet consisting of small invertebrates, but omnivorous species exist and a few feed on plant matter. Frog skin has a rich microbiome which is important to their health. Frogs are extremely efficient at converting what they eat into body mass. They are an important food source for predators and part of the food web dynamics of many of the world's ecosystems. The skin is semi-permeable, making them susceptible to dehydration, so they either live in moist places or have special adaptations to deal with dry habitats. Frogs produce a wide range of vocalizations, particularly in their breeding season, and exhibit many different kinds of complex behaviors to attract mates, to fend off predators and to generally survive. Frogs have a highly developed nervous system that consists of a brain, spinal cord and nerves. Many parts of frog brains correspond with those of humans. It consists of two olfactory lobes, two cerebral hemispheres, a pineal body, two optic lobes, a cerebellum and a medulla oblongata. Muscular coordination and posture are controlled by the cerebellum, and the medulla oblongata regulates respiration, digestion and other automatic functions. The eyes of most frogs are located on either side of the head near the top and project outwards as hemispherical bulges. They provide binocular vision over a field of 100° to the front and a total visual field of almost 360°. They may be the only part of an otherwise submerged frog to protrude from the water. Each eye has closable upper and lower lids and a nictitating membrane which provides further protection, especially when the frog is swimming. Members of the aquatic family Pipidae have the eyes located at the top of the head, a position better suited for detecting prey in the water above. The irises come in a range of colours and the pupils in a range of shapes. The common toad (Bufo bufo) has golden irises and horizontal slit-like pupils, the red-eyed tree frog (Agalychnis callidryas) has vertical slit pupils, the poison dart frog has dark irises, the fire-bellied toad (Bombina spp.) has triangular pupils and the tomato frog (Dyscophus spp.) has circular ones. The irises of the southern toad (Anaxyrus terrestris) are patterned so as to blend in with the surrounding camouflaged skin. The distant vision of a frog is better than its near vision. Calling frogs will quickly become silent when they see an intruder or even a moving shadow but the closer an object is, the less well it is seen. When a frog shoots out its tongue to catch an insect it is reacting to a small moving object that it cannot see well and must line it up precisely beforehand because it shuts its eyes as the tongue is extended. Although it was formerly debated, more recent research has shown that frogs can see in colour, even in very low light. - Wikipedia
What is focus? Focus is the behavioral and cognitive process of selectively concentrating on a discrete aspect of information, whether considered subjective or objective, while ignoring other perceivable information. William James (1890) wrote that "Attention is the taking possession by the mind, in clear and vivid form, of one out of what seem several simultaneously possible objects or trains of thought. Focalization, concentration, of consciousness are of its essence." Attention has also been described as the allocation of limited cognitive processing resources. Attention is manifested by an attentional bottleneck, in term of the amount of data the brain can process each second; for example, in human vision, only less than 1% of the visual input data (at around one megabyte per second) can enter the bottleneck, leading to inattentional blindness. Attention remains a crucial area of investigation within education, psychology, neuroscience, cognitive neuroscience, and neuropsychology. Areas of active investigation involve determining the source of the sensory cues and signals that generate attention, the effects of these sensory cues and signals on the tuning properties of sensory neurons, and the relationship between attention and other behavioral and cognitive processes, which may include working memory and psychological vigilance. A relatively new body of research, which expands upon earlier research within psychopathology, is investigating the diagnostic symptoms associated with traumatic brain injury and its effects on attention. Attention also varies across cultures. The relationships between attention and consciousness are complex enough that they have warranted perennial philosophical exploration. Such exploration is both ancient and continually relevant, as it can have effects in fields ranging from mental health and the study of disorders of consciousness to artificial intelligence and its domains of research. - Wikipedia
What is innocence? Innocence is a lack of guilt, with respect to any kind of crime, or wrongdoing. In a legal context, innocence is to the lack of legal guilt of an individual, with respect to a crime. In other contexts, it is a lack of experience. Innocence can imply lesser experience in either a relative view to social peers, or by an absolute comparison to a more common normative scale. In contrast to ignorance, it is generally viewed as a positive term, connoting an optimistic view of the world, in particular one where the lack of knowledge stems from a lack of wrongdoing, whereas greater knowledge comes from doing wrong. This connotation may be connected with a popular false etymology explaining “innocent” as meaning “not knowing” (Latin noscere (To know, learn)). The actual etymology is from general negation prefix in- and the Latin nocere, “to harm”. People who lack the mental capacity to understand the nature of their acts may be regarded as innocent regardless of their behavior. From this meaning comes the usage of innocent as a noun to refer to a child under the age of reason, or a person, of any age, who is severely mentally disabled. Nonetheless, the word “innocence” is used to describe childhood innocence as a notion created and controlled by adults. As Jean-Jacques Rousseau describes ‘childhood as a time of innocence’ where children are 'not-knowing’ and must reach the age of reason to become competent people in society. However, this is not the case anymore as technology advances, this has given children in the contemporary world a platform where they are referred to as 'digital natives’, where they are seen more knowledgeable than adults. Furthermore, because of digital media and the internet, young people have become well-informed of the world around them and have a better understanding. In some cases, the term “innocence” has a pejorative meaning, where an assumed level of experience dictates common discourse or baseline qualifications for entry into another, different, social experience. Since experience is a prime factor in determining a person’s point of view, innocence is often also used to imply naivety or lack of personal experience.
What is a face? The face is the front of an animal’s head that features three of the head’s sense organs, the eyes, nose, and mouth, and through which animals express many of their emotions. The face is crucial for human identity, and damage such as scarring or developmental deformities affects the psyche adversely. Facial appearance is vital for human recognition and communication. Facial muscles in humans allow expression of emotions.The face is itself a highly sensitive region of the human body and its expression may change when the brain is stimulated by any of the many human senses, such as touch, temperature, smell, taste, hearing, movement, hunger, or visual stimuli.
What is patience? Patience (or forbearance) is the ability to endure difficult circumstances such as perseverance in the face of delay; tolerance of provocation without responding in annoyance/anger; or forbearance when under strain, especially when faced with longer-term difficulties. Patience is the level of endurance one can have before negativity. It is also used to refer to the character trait of being steadfast. Antonyms include hastiness and impetuousness.
What is coincidence? A coincidence is a remarkable concurrence of events or circumstances that have no apparent causal connection with one another. The perception of remarkable coincidences may lead to supernatural, occult, or paranormal claims. Or it may lead to belief in fatalism, which is a doctrine that events will happen in the exact manner of a predetermined plan. From a statistical perspective, coincidences are inevitable and often less remarkable than they may appear intuitively.
What is time? Time is the indefinite continued progress of existence and events that occur in an apparently irreversible succession from the past, through the present, into the future. Time is a component quantity of various measurements used to sequence events, to compare the duration of events or the intervals between them, and to quantify rates of change of quantities in material reality or in the conscious experience. Time is often referred to as a fourth dimension, along with three spatial dimensions. Time has long been an important subject of study in religion, philosophy, and science, but defining it in a manner applicable to all fields without circularity has consistently eluded scholars. Nevertheless, diverse fields such as business, industry, sports, the sciences, and the performing arts all incorporate some notion of time into their respective measuring systems. Time in physics is operationally defined as “what a clock reads”. Time is one of the seven fundamental physical quantities in both the International System of Units and International System of Quantities. Time is used to define other quantities – such as velocity – so defining time in terms of such quantities would result in circularity of definition. An operational definition of time, wherein one says that observing a certain number of repetitions of one or another standard cyclical event (such as the passage of a free-swinging pendulum) constitutes one standard unit such as the second, is highly useful in the conduct of both advanced experiments and everyday affairs of life. To describe observations of an event, a location (position in space) and time are typically noted. The operational definition of time does not address what the fundamental nature of it is. It does not address why events can happen forward and backwards in space, whereas events only happen in the forward progress of time. Investigations into the relationship between space and time led physicists to define the spacetime continuum. General Relativity is the primary framework for understanding how spacetime works. Through advances in both theoretical and experimental investigations of space-time, it has been shown that time can be distorted, particularly at the edges of blackholes. Temporal measurement has occupied scientists and technologists, and was a prime motivation in navigation and astronomy. Periodic events and periodic motion have long served as standards for units of time. Examples include the apparent motion of the sun across the sky, the phases of the moon, the swing of a pendulum, and the beat of a heart. Currently, the international unit of time, the second, is defined by measuring the electronic transition frequency of caesium atoms. Time is also of significant social importance, having economic value (“time is money”) as well as personal value, due to an awareness of the limited time in each day and in human life spans.
What is television? The word television comes from Ancient Greek τῆλε (tèle), meaning ‘far’, and Latin visio, meaning 'sight’. Television (TV), sometimes shortened to tele or telly, is a telecommunication medium used for transmitting moving images in monochrome (black and white), or in colour, and in two or three dimensions and sound. The term can refer to a television set, a television program (“TV show”), or the medium of television transmission. Television is a mass medium for advertising, entertainment and news. Television became available in crude experimental forms in the late 1920s, but it would still be several years before the new technology would be marketed to consumers. After World War II, an improved form of black-and-white TV broadcasting became popular in the United States and Britain, and television sets became commonplace in homes, businesses, and institutions. During the 1950s, television was the primary medium for influencing public opinion. In the mid-1960s, color broadcasting was introduced in the US and most other developed countries. The availability of multiple types of archival storage media such as Betamax and VHS tapes, high-capacity hard disk drives, DVDs, flash drives, high-definition Blu-ray Discs, and cloud digital video recorders has enabled viewers to watch pre-recorded material—such as movies—at home on their own time schedule. For many reasons, especially the convenience of remote retrieval, the storage of television and video programming now occurs on the cloud. At the end of the first decade of the 2000s, digital television transmissions greatly increased in popularity. In 2013, 79% of the world’s households owned a television set.
What is feeling? Feeling is the nominalization of the verb to feel. Originally used in the English language to describe the physical sensation of touch through either experience or perception, the word is also used to describe other experiences, such as “a feeling of warmth" and of sentience in general. In Latin, sentire meant to feel, hear or smell. In psychology, the word is usually reserved for the conscious subjective experience of emotion. Phenomenology and heterophenomenology are philosophical approaches that provide some basis for knowledge of feelings. Many schools of psychotherapy depend on the therapist achieving some kind of understanding of the client’s feelings, for which methodologies exist. Perception of the physical world does not necessarily result in a universal reaction among receivers (emotions), but varies depending upon one’s tendency to handle the situation, how the situation relates to the receiver’s past experiences, and any number of other factors. Feelings are also known as a state of consciousness, such as that resulting from emotions, sentiments or desires. People buy products in hopes that the product will make them feel a certain way: either happy, excited or beautiful. Or, they find the product useful in some way, even indirectly such as to support a charity or for altruistic economic reasons. Some people buy beauty products in hopes of achieving a state of happiness or a sense of self beauty or as an act or expression of beauty. Past events are used in our lives to form schemas in our minds, and based on those past experiences, we expect our lives to follow a certain script. However, storytelling, commemoration and reservation of commemoration (the unwillingness to overtly impose remembrances), research and investigation, and many other activities can help settle uneasy feelings without “scripting”, without the ambivalence that feeling can only be “handled” by proxy, which is not always true. A social psychologist, Daniel Gilbert, conducted a study on the influence of feelings on events alongside other researchers. The results showed that when the participants predicted a positive feeling for an event, the higher the chances that they wanted to relive the event. Predicted feelings were either short-lived or did not correlate to what the participant expected. Individuals in society predict that something will give them a certain desired outcome or feeling. Indulging in what one might have thought would’ve made them happy or excited might only cause a temporary thrill, or it might result in the opposite of what was expected. Events and experiences are done and relived to satisfy one’s feelings.Details and information about the past is used to make decisions, as past experiences of feelings influence current decision-making, how people will feel in the future, and if they want to feel that way again.
What is evil? Evil, in a general sense, is the opposite or absence of good. It can be an extremely broad concept, although in everyday usage is often used more narrowly to denote profound wickedness. It is generally seen as taking multiple possible forms, such as the form of personal moral evil commonly associated with the word, or impersonal natural evil (as in the case of natural disasters or illnesses), and in religious thought, the form of the demonic or supernatural/eternal. Evil can denote profound immorality, but typically not without some basis in the understanding of the human condition, where strife and suffering (cf. Hinduism) are the true roots of evil. In certain religious contexts, evil has been described as a supernatural force. Definitions of evil vary, as does the analysis of its motives. Elements that are commonly associated with personal forms of evil involve unbalanced behavior involving anger, revenge, fear, hatred, psychological trauma, expediency, selfishness, ignorance, destruction or neglect. Evil is sometimes perceived as the dualistic antagonistic binary opposite to good, in which good should prevail and evil should be defeated. In cultures with Buddhist spiritual influence, both good and evil are perceived as part of an antagonistic duality that itself must be overcome through achieving Nirvana. The philosophical questions regarding good and evil are subsumed into three major areas of study: Meta-ethics concerning the nature of good and evil, Normative ethics concerning how we ought to behave, and Applied ethics concerning particular moral issues. While the term is applied to events and conditions without agency, the forms of evil addressed in this article presume an evildoer or doers. Some religions and philosophies deny evil’s existence and usefulness in describing people.
What are tears? Tears are a clear liquid secreted by the lacrimal glands (tear gland) found in the eyes of all land mammals (except for goats and rabbits). Their functions include lubricating the eyes (basal tears), removing irritants (reflex tears), and aiding the immune system. Tears also occur as a part of the body's natural pain response. Humans are the only mammals known to produce tears as part of an emotional response, such as out of joy or grief. Tears have symbolic significance among humans (see crying). Emotional secretion of tears may serve a biological function by excreting stress-inducing hormones built up through times of emotional distress. Tears are made up of water, electrolytes, proteins, lipids, and mucins that form layers on the surface of eyes. The different types of tears—basal, reflex, and emotional—vary significantly in composition. Tears are made up of three layers: lipid, aqueous, and mucous. Tears are composed of water, salts, antibodies, and lysozymes (antibacterial enzymes), though composition varies among different tear types. The composition of tears caused by emotion differs from that of tears as a reaction to irritants, such as onion fumes, dust, or allergy. Emotional tears contain higher concentrations of stress hormones such as adrenocorticotropic hormone and leucine enkephalin (a natural pain killer), which suggests that emotional tears play a biological role in balancing stress hormone levels.
What is a window? A window is an opening in a wall, door, roof, or vehicle that allows the passage of light and may also allow the passage of sound and sometimes air. Modern windows are usually glazed or covered in some other transparent or translucent material, a sash set in a frame in the opening; the sash and frame are also referred to as a window. Many glazed windows may be opened, to allow ventilation, or closed, to exclude inclement weather. Windows may have a latch or similar mechanism to lock the window shut or to hold it open by various amounts. Types include the eyebrow window, fixed windows, hexagonal windows, single-hung, and double-hung sash windows, horizontal sliding sash windows, casement windows, awning windows, hopper windows, tilt, and slide windows (often door-sized), tilt and turn windows, transom windows, sidelight windows, jalousie or louvered windows, clerestory windows, lancet windows, skylights, roof windows, roof lanterns, bay windows, oriel windows, thermal, or Diocletian, windows, picture windows, Rose windows, emergency exit windows, stained glass windows, French windows, panel windows, double/triple-paned windows, and witch windows. The Romans were the first known to use glass for windows, a technology likely first produced in Roman Egypt, in Alexandria ca. 100 AD. Paper windows were economical and widely used in ancient China, Korea, and Japan. In England, glass became common in the windows of ordinary homes only in the early 17th century whereas windows made up of panes of flattened animal horn were used as early as the 14th century. In the 19th century American west, greased paper windows came to be used by itinerant groups. Modern-style floor-to-ceiling windows became possible only after the industrial plate glass making processes were fully perfected. - Wikipedia
What is ice? Ice is water frozen into a solid state. Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opaque bluish-white color. In the Solar System, ice is abundant and occurs naturally from as close to the Sun as Mercury to as far away as the Oort cloud objects. Beyond the Solar System, it occurs as interstellar ice. It is abundant on Earth's surface – particularly in the polar regions and above the snow line – and, as a common form of precipitation and deposition, plays a key role in Earth's water cycle and climate. It falls as snowflakes and hail or occurs as frost, icicles or ice spikes and aggregates from snow as glaciers and ice sheets. Ice exhibits at least eighteen phases (packing geometries), depending on temperature and pressure. When water is cooled rapidly (quenching), up to three types of amorphous ice can form depending on its history of pressure and temperature. When cooled slowly, correlated proton tunneling occurs below −253.15 °C (20 K, −423.67 °F) giving rise to macroscopic quantum phenomena. Virtually all ice on Earth's surface and in its atmosphere is of a hexagonal crystalline structure denoted as ice Ih (spoken as "ice one h") with minute traces of cubic ice, denoted as ice Ic and, more recently found, Ice VII inclusions in diamonds. The most common phase transition to ice Ih occurs when liquid water is cooled below 0 °C (273.15 K, 32 °F) at standard atmospheric pressure. It may also be deposited directly by water vapor, as happens in the formation of frost. The transition from ice to water is melting and from ice directly to water vapor is sublimation. Ice is used in a variety of ways, including for cooling, for winter sports, and ice sculpting.
What is a bubble? A bubble is a globule of one substance in another, usually gas in a liquid. Due to the Marangoni effect, bubbles may remain intact when they reach the surface of the immersive substance. Bubbles are visible because they have a different refractive index (RI) than the surrounding substance. For example, the RI of air is approximately 1.0003 and the RI of water is approximately 1.333. Snell's Law describes how electromagnetic waves change direction at the interface between two mediums with different IR; thus bubbles can be identified from the accompanying refraction and internal reflection even though both the immersed and immersing mediums are transparent. The above explanation only holds for bubbles of one medium submerged in another medium (e.g. bubbles of gas in a soft drink); the volume of a membrane bubble (e.g. soap bubble) will not distort light very much, and one can only see a membrane bubble due to thin-film diffraction and reflection. When bubbles are disturbed (for example when a gas bubble is injected underwater), the wall oscillates. Although it is often visually masked by much larger deformations in shape, a component of the oscillation changes the bubble volume (i.e. it is pulsation) which, in the absence of an externally-imposed sound field, occurs at the bubble's natural frequency. The pulsation is the most important component to the oscillation, acoustically, because by changing the gas volume, it changes its pressure, and leads to the emission of sound at the bubble's natural frequency. For air bubbles in water, large bubbles (negligible surface tension and thermal conductivity) undergo adiabatic pulsations, which means that no heat is transferred either from the liquid to the gas or vice versa. The natural frequency of such bubbles is determined by the equation - Wikipedia
What is a cat? The cat (Felis catus) is a domestic species of small carnivorous mammal. It is the only domesticated species in the family Felidae and is often referred to as the domestic cat to distinguish it from the wild members of the family A cat can either be a house cat, a farm cat or a feral cat; the latter ranges freely and avoids human contact. Domestic cats are valued by humans for companionship and their ability to hunt rodents. About 60 cat breeds are recognized by various cat registries. The cat is similar in anatomy to the other felid species: it has a strong flexible body, quick reflexes, sharp teeth and retractable claws adapted to killing small prey. Its night vision and sense of smell are well developed. Cat communication includes vocalizations like meowing, purring, trilling, hissing, growling and grunting as well as cat-specific body language. A predator that is most active at dawn and dusk, the cat is a solitary hunter but a social species. It can hear sounds too faint or too high in frequency for human ears, such as those made by mice and other small mammals. It secretes and perceives pheromones. Female domestic cats can have kittens from spring to late autumn, with litter sizes often ranging from two to five kittens. Domestic cats are bred and shown at events as registered pedigreed cats, a hobby known as cat fancy. Failure to control breeding of pet cats by spaying and neutering, as well as abandonment of pets, resulted in large numbers of feral cats worldwide, contributing to the extinction of entire bird, mammal, and reptile species, and evoking population control. Cats were first domesticated in the Near East around 7500 BC. It was long thought that cat domestication was initiated in ancient Egypt, as since around 3100 BC veneration was given to cats in ancient Egypt. As of 2021 there are an estimated 220 million owned and 480 million stray cats in the world. As of 2017, the domestic cat was the second-most popular pet in the United States, with 95 million cats owned. In the United Kingdom, 26% of UK adults have a cat with an estimated population of 10.9 million pet cats as of 2020.
What is advertising? Advertising is a marketing communication that employs an openly sponsored, non-personal message to promote or sell a product, service or idea. Sponsors of advertising are typically businesses wishing to promote their products or services. Advertising is differentiated from public relations in that an advertiser pays for and has control over the message. It differs from personal selling in that the message is non-personal, i.e., not directed to a particular individual. Advertising is communicated through various mass media, including traditional media such as newspapers, magazines, television, radio, outdoor advertising or direct mail; and new media such as search results, blogs, social media, websites or text messages. The actual presentation of the message in a medium is referred to as an advertisement: advert or ad for short. Commercial ads often seek to generate increased consumption of their products or services through "branding", which associates a product name or image with certain qualities in the minds of consumers. On the other hand, ads that intend to elicit an immediate sale are known as direct-response advertising. Non-commercial entities that advertise more than consumer products or services include political parties, interest groups, religious organizations and governmental agencies. Non-profit organizations may use free modes of persuasion, such as a public service announcement. Advertising may also help to reassure employees or shareholders that a company is viable or successful. Modern advertising originated with the techniques introduced with tobacco advertising in the 1920s, most significantly with the campaigns of Edward Bernays, considered the founder of modern, "Madison Avenue" advertising. Worldwide spending on advertising in 2015 amounted to an estimated US$529.43 billion. Advertising's projected distribution for 2017 was 40.4% on TV, 33.3% on digital, 9% on newspapers, 6.9% on magazines, 5.8% on outdoor and 4.3% on radio. Internationally, the largest ("Big Five") advertising-agency groups are Dentsu, Interpublic, Omnicom, Publicis, and WPP. In Latin, advertere means "to turn towards". - Wikipedia
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Magnoliophyta, also called angiosperms). The biological function of a flower is to facilitate reproduction, usually by providing a mechanism for the union of sperm with eggs. Flowers may facilitate outcrossing (fusion of sperm and eggs from different individuals in a population) resulting from cross pollination or allow selfing (fusion of sperm and egg from the same flower) when self pollination occurs. Pollination have two types which is self-pollination and cross-pollination. Self-pollination happens when the pollen from the anther is deposited on the stigma of the same flower, or another flower on the same plant. Cross-pollination is the transfer of pollen from the anther of one flower to the stigma of another flower on a different individual of the same species. Self-pollination happened in flowers where the stamen and carpel mature at the same time, and are positioned so that the pollen can land on the flower’s stigma. This pollination does not require an investment from the plant to provide nectar and pollen as food for pollinators. Some flowers produce diaspores without fertilization (parthenocarpy). Flowers contain sporangia and are the site where gametophytes develop. Many flowers have evolved to be attractive to animals, so as to cause them to be vectors for the transfer of pollen. After fertilization, the ovary of the flower develops into fruit containing seeds. In addition to facilitating the reproduction of flowering plants, flowers have long been admired and used by humans to bring beauty to their environment, and also as objects of romance, ritual, religion, medicine and as a source of food.
What is rain? Rain is liquid water in the form of droplets that have condensed from atmospheric water vapor and then become heavy enough to fall under gravity. Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the Earth. It provides suitable conditions for many types of ecosystems, as well as water for hydroelectric power plants and crop irrigation. The major cause of rain production is moisture moving along three-dimensional zones of temperature and moisture contrasts known as weather fronts. If enough moisture and upward motion is present, precipitation falls from convective clouds (those with strong upward vertical motion) such as cumulonimbus (thunder clouds) which can organize into narrow rainbands. In mountainous areas, heavy precipitation is possible where upslope flow is maximized within windward sides of the terrain at elevation which forces moist air to condense and fall out as rainfall along the sides of mountains. On the leeward side of mountains, desert climates can exist due to the dry air caused by downslope flow which causes heating and drying of the air mass. The movement of the monsoon trough, or intertropical convergence zone, brings rainy seasons to savannah climes. The urban heat island effect leads to increased rainfall, both in amounts and intensity, downwind of cities. Global warming is also causing changes in the precipitation pattern globally, including wetter conditions across eastern North America and drier conditions in the tropics. Antarctica is the driest continent. The globally averaged annual precipitation over land is 715 mm (28.1 in), but over the whole Earth it is much higher at 990 mm (39 in). Climate classification systems such as the Köppen classification system use average annual rainfall to help differentiate between differing climate regimes. Rainfall is measured using rain gauges. Rainfall amounts can be estimated by weather radar. Rain is also known or suspected on other planets, where it may be composed of methane, neon, sulfuric acid, or even iron rather than water. - Wikipedia
What is a bat? Bats are mammals of the order Chiroptera.[a] With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more manoeuvrable than birds, flying with their very long spread-out digits covered with a thin membrane or patagium. The smallest bat, and arguably the smallest extant mammal, is Kitti's hog-nosed bat, which is 29–34 millimetres (1 1⁄8–1 3⁄8 inches) in length, 150 mm (6 in) across the wings and 2–2.6 g (1⁄16–3⁄32 oz) in mass. The largest bats are the flying foxes and the giant golden-crowned flying fox, Acerodon jubatus, which can weigh 1.6 kg (3 1⁄2 lb) and have a wingspan of 1.7 m (5 ft 7 in). The second largest order of mammals after rodents, bats comprise about 20% of all classified mammal species worldwide, with over 1,400 species. These were traditionally divided into two suborders: the largely fruit-eating megabats, and the echolocating microbats. But more recent evidence has supported dividing the order into Yinpterochiroptera and Yangochiroptera, with megabats as members of the former along with several species of microbats. Many bats are insectivores, and most of the rest are frugivores (fruit-eaters) or nectarivores (nectar-eaters). A few species feed on animals other than insects; for example, the vampire bats feed on blood. Most bats are nocturnal, and many roost in caves or other refuges; it is uncertain whether bats have these behaviours to escape predators. Bats are present throughout the world, with the exception of extremely cold regions. They are important in their ecosystems for pollinating flowers and dispersing seeds; many tropical plants depend entirely on bats for these services. Bats provide humans with some direct benefits, at the cost of some disadvantages. Bat dung has been, and in many places, is still mined as guano from caves and used as fertiliser. Bats consume insect pests, reducing the need for pesticides and other insect management measures. They are sometimes numerous enough and close enough to human settlements to serve as tourist attractions, and they are used as food across Asia and the Pacific Rim. However, fruit bats are frequently considered pests by fruit growers. Due to their physiology, bats are one type of animal that acts as a natural reservoir of many pathogens, such as rabies; and since they are highly mobile, social, and long-lived, they can readily spread disease among themselves. If humans interact with bats, these traits become potentially dangerous to humans. Depending on the culture, bats may be symbolically associated with positive traits, such as protection from certain diseases or risks, rebirth, or long life, but in the West, bats are popularly associated with darkness, malevolence, witchcraft, vampires, and death. - Wikipedia
What is a toy? A toy is an item that is used in play, especially one designed for such use. It is mainly intended for use by children, though may also be marketed to adults under certain circumstances. Playing with toys can be an enjoyable means of training young children for life in society. Different materials like wood, clay, paper, and plastic are used to make toys. Many items are designed to serve as toys, but goods produced for other purposes can also be used. For instance, a small child may fold an ordinary piece of paper into an airplane shape and "fly it". Newer forms of toys include interactive digital entertainment. Some toys are produced primarily as collectors' items and are intended for display only. The origin of toys is prehistoric; dolls representing infants, animals, and soldiers, as well as representations of tools used by adults are readily found at archaeological sites. The origin of the word "toy" is unknown, but it is believed that it was first used in the 14th century. Toys are mainly made for children. The oldest known doll toy is thought to be 4,000 years old. Playing with toys is considered to be important when it comes to growing up and learning about the world around us. Younger children use toys to discover their identity, help their bodies grow strong, learn cause and effect, explore relationships, and practice skills they will need as adults. Adults on occasion use toys to form and strengthen social bonds, teach, help in therapy, and to remember and reinforce lessons from their youth.
What is a computer? A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations automatically. Modern computers can perform generic sets of operations known as programs. These programs enable computers to perform a wide range of tasks. A computer system is a "complete" computer that includes the hardware, operating system (main software), and peripheral equipment needed and used for "full" operation. This term may also refer to a group of computers that are linked and function together, such as a computer network or computer cluster. A broad range of industrial and consumer products use computers as control systems. Simple special-purpose devices like microwave ovens and remote controls are included, as are factory devices like industrial robots and computer-aided design, as well as general-purpose devices like personal computers and mobile devices like smartphones. Computers power the Internet, which links hundreds of millions of other computers and users. Early computers were only meant to be used for calculations. Simple manual instruments like the abacus have aided people in doing calculations since ancient times. Early in the Industrial Revolution, some mechanical devices were built to automate long tedious tasks, such as guiding patterns for looms. More sophisticated electrical machines did specialized analog calculations in the early 20th century. The first digital electronic calculating machines were developed during World War II. The first semiconductor transistors in the late 1940s were followed by the silicon-based MOSFET (MOS transistor) and monolithic integrated circuit (IC) chip technologies in the late 1950s, leading to the microprocessor and the microcomputer revolution in the 1970s. The speed, power and versatility of computers have been increasing dramatically ever since then, with transistor counts increasing at a rapid pace (as predicted by Moore's law), leading to the Digital Revolution during the late 20th to early 21st centuries. Conventionally, a modern computer consists of at least one processing element, typically a central processing unit (CPU) in the form of a microprocessor, along with some type of computer memory, typically semiconductor memory chips. The processing element carries out arithmetic and logical operations, and a sequencing and control unit can change the order of operations in response to stored information. Peripheral devices include input devices (keyboards, mice, joystick, etc.), output devices (monitor screens, printers, etc.), and input/output devices that perform both functions (e.g., the 2000s-era touchscreen). Peripheral devices allow information to be retrieved from an external source and they enable the result of operations to be saved and retrieved.
What is a shower? A shower is a place in which a person bathes under a spray of typically warm or hot water. Indoors, there is a drain in the floor. Most showers have temperature, spray pressure and adjustable showerhead nozzle. The simplest showers have a swivelling nozzle aiming down on the user, while more complex showers have a showerhead connected to a hose that has a mounting bracket. This allows the showerer to hold the showerhead by hand to spray the water at different parts of their body. A shower can be installed in a small shower stall or bathtub with a plastic shower curtain or door. Showering is common in Western culture due to the efficiency of using it compared with a bathtub. Its use in hygiene is, therefore, common practice. A shower uses less water on average than a bath: 80 litres for a shower compared with 150 litres for a bath. The original showers were neither indoor structures nor man-made but were common natural formations: waterfalls. The falling water rinsed the bathers completely clean and was more efficient than bathing in a traditional basin, which required manual transport of both fresh and waste water. Ancient people began to reproduce these natural phenomena by pouring jugs of water, often very cold, over themselves after washing. There has been evidence of early upper class Egyptian and Mesopotamians having indoor shower rooms where servants would bathe them in the privacy of their own homes. However, these were rudimentary by modern standards, having rudimentary drainage systems and water was carried, not pumped, into the room. The ancient Greeks were the first people to have showers. Their aqueducts and sewage systems made of lead pipes allowed water to be pumped both into and out of large communal shower rooms used by elites and common citizens alike. These rooms have been discovered at the site of the city Pergamum and can also be found represented in pottery of the era. The depictions are very similar to modern locker room showers, and even included bars to hang up clothing. The ancient Romans also followed this convention; their famous bathhouses (Thermae) can be found all around the Mediterranean and as far out as modern-day England. The Romans not only had these showers but also believed in bathing multiple times a week, if not every day. The water and sewage systems developed by the Greeks and Romans broke down and fell out of use after the fall of the Roman Empire. - Wikipedia
What is fire? Fire is the rapid oxidation of a material in the exothermic chemical process of combustion, releasing heat, light, and various reaction products. Fire is hot because the conversion of the weak double bond in molecular oxygen, O2, to the stronger bonds in the combustion products carbon dioxide and water releases energy (418 kJ per 32 g of O2); the bond energies of the fuel play only a minor role here. At a certain point in the combustion reaction, called the ignition point, flames are produced. The flame is the visible portion of the fire. Flames consist primarily of carbon dioxide, water vapor, oxygen and nitrogen. If hot enough, the gases may become ionized to produce plasma. Depending on the substances alight, and any impurities outside, the color of the flame and the fire's intensity will be different. Fire in its most common form can result in conflagration, which has the potential to cause physical damage through burning. Fire is an important process that affects ecological systems around the globe. The positive effects of fire include stimulating growth and maintaining various ecological systems. Its negative effects include hazard to life and property, atmospheric pollution, and water contamination. If fire removes protective vegetation, heavy rainfall may lead to an increase in soil erosion by water. Also, when vegetation is burned, the nitrogen it contains is released into the atmosphere, unlike elements such as potassium and phosphorus which remain in the ash and are quickly recycled into the soil. This loss of nitrogen caused by a fire produces a long-term reduction in the fertility of the soil, but this fecundity can potentially be recovered as molecular nitrogen in the atmosphere is "fixed" and converted to ammonia by natural phenomena such as lightning and by leguminous plants that are "nitrogen-fixing" such as clover, peas, and green beans. Fire has been used by humans in rituals, in agriculture for clearing land, for cooking, generating heat and light, for signaling, propulsion purposes, smelting, forging, incineration of waste, cremation, and as a weapon or mode of destruction. Fires start when a flammable or a combustible material, in combination with a sufficient quantity of an oxidizer such as oxygen gas or another oxygen-rich compound (though non-oxygen oxidizers exist), is exposed to a source of heat or ambient temperature above the flash point for the fuel/oxidizer mix, and is able to sustain a rate of rapid oxidation that produces a chain reaction. This is commonly called the fire tetrahedron. Fire cannot exist without all of these elements in place and in the right proportions. For example, a flammable liquid will start burning only if the fuel and oxygen are in the right proportions. Some fuel-oxygen mixes may require a catalyst, a substance that is not consumed, when added, in any chemical reaction during combustion, but which enables the reactants to combust more readily. Once ignited, a chain reaction must take place whereby fires can sustain their own heat by the further release of heat energy in the process of combustion and may propagate, provided there is a continuous supply of an oxidizer and fuel. If the oxidizer is oxygen from the surrounding air, the presence of a force of gravity, or of some similar force caused by acceleration, is necessary to produce convection, which removes combustion products and brings a supply of oxygen to the fire. Without gravity, a fire rapidly surrounds itself with its own combustion products and non-oxidizing gases from the air, which exclude oxygen and extinguish the fire. Because of this, the risk of fire in a spacecraft is small when it is coasting in inertial flight. This does not apply if oxygen is supplied to the fire by some process other than thermal convection. The ability to control fire was a dramatic change in the habits of early humans. Making fire to generate heat and light made it possible for people to cook food, simultaneously increasing the variety and availability of nutrients and reducing disease by killing organisms in the food. The heat produced would also help people stay warm in cold weather, enabling them to live in cooler climates. Fire also kept nocturnal predators at bay. Evidence of cooked food is found from 1 million years ago, although fire was probably not used in a controlled fashion until 400,000 years ago. There is some evidence that fire may have been used in a controlled fashion about 1 million years ago. Evidence becomes widespread around 50 to 100 thousand years ago, suggesting regular use from this time; interestingly, resistance to air pollution started to evolve in human populations at a similar point in time. The use of fire became progressively more sophisticated, with it being used to create charcoal and to control wildlife from 'tens of thousands' of years ago. - Wikipedia
What is religion? Religion is a social-cultural system of designated behaviors and practices, morals, worldviews, texts, sanctified places, prophecies, ethics, or organizations, that relates humanity to supernatural, transcendental, and spiritual elements. However, there is no scholarly consensus over what precisely constitutes a religion. Different religions may or may not contain various elements ranging from the divine, sacred things, faith, a supernatural being or supernatural beings or "some sort of ultimacy and transcendence that will provide norms and power for the rest of life". Religious practices may include rituals, sermons, commemoration or veneration (of deities and/or saints), sacrifices, festivals, feasts, trances, initiations, funerary services, matrimonial services, meditation, prayer, music, art, dance, public service, or other aspects of human culture. Religions have sacred histories and narratives, which may be preserved in sacred scriptures, and symbols and holy places, that aim mostly to give a meaning to life. Religions may contain symbolic stories, which are sometimes said by followers to be true, that have the side purpose of explaining the origin of life, the universe, and other things. Traditionally, faith, in addition to reason, has been considered a source of religious beliefs. There are an estimated 10,000 distinct religions worldwide. About 84% of the world's population is affiliated with Christianity, Islam, Hinduism, Buddhism, or some form of folk religion. The religiously unaffiliated demographic includes those who do not identify with any particular religion, atheists, and agnostics. While the religiously unaffiliated have grown globally, many of the religiously unaffiliated still have various religious beliefs. The study of religion encompasses a wide variety of academic disciplines, including theology, comparative religion and social scientific studies. Theories of religion offer various explanations for the origins and workings of religion, including the ontological foundations of religious being and belief. - Wikipedia
What is a voice? The human voice consists of sound made by a human being using the vocal tract, including talking, singing, laughing, crying, screaming, shouting, or yelling. The human voice frequency is specifically a part of human sound production in which the vocal folds (vocal cords) are the primary sound source. (Other sound production mechanisms produced from the same general area of the body involve the production of unvoiced consonants, clicks, whistling and whispering.) Generally speaking, the mechanism for generating the human voice can be subdivided into three parts; the lungs, the vocal folds within the larynx (voice box), and the articulators. The lungs, the "pump" must produce adequate airflow and air pressure to vibrate vocal folds. The vocal folds (vocal cords) then vibrate to use airflow from the lungs to create audible pulses that form the laryngeal sound source. The muscles of the larynx adjust the length and tension of the vocal folds to ‘fine-tune’ pitch and tone. The articulators (the parts of the vocal tract above the larynx consisting of tongue, palate, cheek, lips, etc.) articulate and filter the sound emanating from the larynx and to some degree can interact with the laryngeal airflow to strengthen or weaken it as a sound source. The vocal folds, in combination with the articulators, are capable of producing highly intricate arrays of sound. The tone of voice may be modulated to suggest emotions such as anger, surprise, fear, happiness or sadness. The human voice is used to express emotion, and can also reveal the age and sex of the speaker. Singers use the human voice as an instrument for creating music. The sound of each individual's voice is entirely unique not only because of the actual shape and size of an individual's vocal cords but also due to the size and shape of the rest of that person's body, especially the vocal tract, and the manner in which the speech sounds are habitually formed and articulated. (It is this latter aspect of the sound of the voice that can be mimicked by skilled performers.) Humans have vocal folds that can loosen, tighten, or change their thickness, and over which breath can be transferred at varying pressures. The shape of chest and neck, the position of the tongue, and the tightness of otherwise unrelated muscles can be altered. Any one of these actions results in a change in pitch, volume, timbre, or tone of the sound produced. Sound also resonates within different parts of the body, and an individual's size and bone structure can affect somewhat the sound produced by an individual.
What is Glass? Glass is a non-crystalline, often transparent amorphous solid, that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics. Glass is most often formed by rapid cooling (quenching) of the molten form; some glasses such as volcanic glass are naturally occurring. The most familiar, and historically the oldest, types of manufactured glass are "silicate glasses" based on the chemical compound silica (silicon dioxide, or quartz), the primary constituent of sand. Soda-lime glass, containing around 70% silica, accounts for around 90% of manufactured glass. The term glass, in popular usage, is often used to refer only to this type of material, although silica-free glasses often have desirable properties for applications in modern communications technology. Some objects, such as drinking glasses and eyeglasses, are so commonly made of silicate-based glass that they are simply called by the name of the material. The history of glass-making dates back to at least 3,600 BC in Mesopotamia, however some claim they may have been producing copies of glass objects from Egypt. Other archaeological evidence suggests that the first true glass was made in coastal north Syria, Mesopotamia or Egypt. The earliest known glass objects, of the mid 2,000 BC, were beads, perhaps initially created as the accidental by-products of metal-working (slags) or during the production of faience, a pre-glass vitreous material made by a process similar to glazing. Glass products remained a luxury until the disasters that overtook the late Bronze Age civilizations seemingly brought glass-making to a halt. Development of glass technology in India may have begun in 1,730 BC. In Ancient China glass-making had a later start compared to ceramics and metal work. From across the former Roman Empire archaeologists have recovered glass objects that were used in domestic, industrial and funerary contexts. Anglo-Saxon glass has been found across England during archaeological excavations of both settlement and cemetery sites. Glass in the Anglo-Saxon period was used in the manufacture of a range of objects including vessels, beads, windows and was even used in jewelry. Naturally occurring glass, especially the volcanic glass obsidian, has been used by many Stone Age societies across the globe for the production of sharp cutting tools and, due to its limited source areas, was extensively traded. But in general, archaeological evidence suggests that the first true glass was made in coastal north Syria, Mesopotamia or ancient Egypt. Because of Egypt's favorable environment for preservation, the majority of well-studied early glass is found there, although some of this is likely to have been imported. The earliest known glass objects, of the mid-third millennium BC, were beads, perhaps initially created as accidental by-products of metal-working (slags) or during the production of faience, a pre-glass vitreous material made by a process similar to glazing. - Wikipedia
What is jealousy? Jealousy generally refers to the thoughts or feelings of insecurity, fear, and concern over a relative lack of possessions or safety. Jealousy can consist of one or more emotions such as anger, resentment, inadequacy, helplessness or disgust. In its original meaning, jealousy is distinct from envy, though the two terms have popularly become synonymous in the English language, with jealousy now also taking on the definition originally used for envy alone. Jealousy is a typical experience in human relationships, and it has been observed in infants as young as five months. Some researchers claim that jealousy is seen in all cultures and is a universal trait. However, others claim jealousy is a culture-specific emotion. Jealousy can either be suspicious or reactive, and it is often reinforced as a series of particularly strong emotions and constructed as a universal human experience. Psychologists have proposed several models to study the processes underlying jealousy and have identified factors that result in jealousy. Sociologists have demonstrated that cultural beliefs and values play an important role in determining what triggers jealousy and what constitutes socially acceptable expressions of jealousy. Biologists have identified factors that may unconsciously influence the expression of jealousy. Throughout history, artists have also explored the theme of jealousy in photographs, paintings, films, songs, plays, poems, and books, and theologians have offered religious views of jealousy based on the scriptures of their respective faiths.
What is empathy? Empathy is the capacity to understand or feel what another person is experiencing from within their frame of reference, that is, the capacity to place oneself in another's position. Definitions of empathy encompass a broad range of emotional states. Types of empathy include cognitive empathy, emotional (or affective) empathy, somatic, and spiritual empathy.
What is a seashell? A seashell or sea shell, also known simply as a shell, is a hard, protective outer layer usually created by an animal that lives in the sea. The shell is part of the body of the animal. Empty seashells are often found washed up on beaches by beachcombers. The shells are empty because the animal has died and the soft parts have decomposed or been eaten by another animal. A seashell is usually the exoskeleton of an invertebrate (an animal without a backbone), and is typically composed of calcium carbonate or chitin. Most shells that are found on beaches are the shells of marine mollusks, partly because these shells are usually made of calcium carbonate, and endure better than shells made of chitin. Apart from mollusk shells, other shells that can be found on beaches are those of barnacles, horseshoe crabs and brachiopods. Marine annelid worms in the family Serpulidae create shells which are tubes made of calcium carbonate cemented onto other surfaces. The shells of sea urchins are called "tests", and the moulted shells of crabs and lobsters are exuviae. While most seashells are external, some cephalopods have internal shells. Seashells have been used by humans for many different purposes throughout history and prehistory. However, seashells are not the only kind of shells; in various habitats, there are shells from freshwater animals such as freshwater mussels and freshwater snails, and shells of land snails.
What is an ear? The ear is the organ that enables hearing and, in mammals, balance. In mammals, the ear is usually described as having three parts—the outer ear, the middle ear and the inner ear. The outer ear consists of the pinna and the ear canal. Since the outer ear is the only visible portion of the ear in most animals, the word "ear" often refers to the external part alone. The middle ear includes the tympanic cavity and the three ossicles. The inner ear sits in the bony labyrinth, and contains structures which are key to several senses: the semicircular canals, which enable balance and eye tracking when moving; the utricle and saccule, which enable balance when stationary; and the cochlea, which enables hearing. The ears of vertebrates are placed somewhat symmetrically on either side of the head, an arrangement that aids sound localisation. The ear develops from the first pharyngeal pouch and six small swellings that develop in the early embryo called otic placodes, which are derived from ectoderm. The ear may be affected by disease, including infection and traumatic damage. Diseases of the ear may lead to hearing loss, tinnitus and balance disorders such as vertigo, although many of these conditions may also be affected by damage to the brain or neural pathways leading from the ear. The ear has been adorned by earrings and other jewelry in numerous cultures for thousands of years, and has been subjected to surgical and cosmetic alterations.
What is self-hate? Self-hate is personal self-loathing or hatred of oneself, or low self-esteem which may lead to self-harm. The term "self-hatred" is used infrequently by psychologists and psychiatrists, who would usually describe people who hate themselves as "people with low self-esteem". Self-hatred, self-guilt and shame are important factors in some or many mental disorders, especially disorders that involve a perceived defect of oneself (e.g. body dysmorphic disorder). Self-hatred is also a symptom of many personality disorders, including borderline personality disorder, as well as mood disorders like depression. It can also be linked to guilt for someone's own actions that they view as wrongful, e.g., survivor guilt.
What is music? Music is the art of arranging sounds in time through the elements of melody, harmony, rhythm, and timbre. It is one of the universal cultural aspects of all human societies. General definitions of music include common elements such as pitch (which governs melody and harmony), rhythm (and its associated concepts tempo, meter, and articulation), dynamics (loudness and softness), and the sonic qualities of timbre and texture (which are sometimes termed the "color" of a musical sound). Different styles or types of music may emphasize, de-emphasize or omit some of these elements. Music is performed with a vast range of instruments and vocal techniques ranging from singing to rapping; there are solely instrumental pieces, solely vocal pieces (such as songs without instrumental accompaniment) and pieces that combine singing and instruments. The word derives from Greek μουσική (mousiké; "(art) of the Muses"). In its most general form, the activities describing music as an art form or cultural activity include the creation of works of music (songs, tunes, symphonies, and so on), the criticism of music, the study of the history of music, and the aesthetic examination of music. Ancient Greek and Indian philosophers defined music in two parts: melodies, as tones ordered horizontally, and harmonies as tones ordered vertically. Common sayings such as "the harmony of the spheres" and "it is music to my ears" point to the notion that music is often ordered and pleasant to listen to. However, 20th-century composer John Cage thought that any sound can be music, saying, for example, "There is no noise, only sound."
Maurice is online.