Music

Music is an art form and cultural activity whose medium is sound and silence. The common elements of music are 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 with vocal techniques ranging from singing to rapping, and there are solely instrumental pieces, solely vocal pieces and pieces that combine singing and instruments. The word derives from Greek μουσική (mousike; "art of the Muses"). In its most general form, the activities describing music as an art form include the production 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 as tones ordered horizontally as melodies and vertically as harmonies. 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."

Sleep

Sleep is a naturally recurring state of mind characterized by altered consciousness, relatively inhibited sensory activity, inhibition of nearly all voluntary muscles, and reduced interactions with surroundings. It is distinguished from wakefulness by a decreased ability to react to stimuli, but is more easily reversed than the state of hibernation or of being comatose. Mammalian sleep occurs in repeating periods, in which the body alternates between two highly distinct modes known as non-REM and REM sleep. REM stands for "rapid eye movement" but involves many other aspects including virtual paralysis of the body.

During sleep, most systems in an animal are in an anabolic state, building up the immune, nervous, skeletal, and muscular systems. Sleep in non-human animals is observed in mammals, birds, reptiles, amphibians, and fish, and, in some form, in insects and even in simpler animals such as nematodes. The internal circadian clock promotes sleep daily at night in diurnal species (such as humans) and in the day in nocturnal organisms (such as rodents). However, sleep patterns vary widely among animals and among different individual humans. Industrialization and artificial light have substantially altered human sleep habits in the last 100 years.

Instrumental

An instrumental is a musical composition or recording without lyrics, or singing, although it might include some inarticulate vocal input; the music is primarily or exclusively produced by musical instruments.

In a song that is otherwise sung, a section not sung but played with instruments can be called an instrumental interlude. If the instruments are percussion instruments, the interlude can be called a percussion interlude. These interludes are a form of break in the song.

In popular music

In commercial popular music, instrumental tracks are sometimes renderings of a corresponding release that features vocals, but they may also be compositions originally conceived without vocals. An instrumental version of a song which otherwise features vocals is also known as a -1 (pronounced minus one).

The opposite of instrumental music is a cappella.

For genres in which a non-vocal song or interlude is conceived using electronic media, rather than with true musical instruments, the term instrumental is nonetheless used for it.

Classical music

Classical music is art music produced or rooted in the traditions of Western music, including both liturgical (religious) and secular music. While a similar term is also used to refer to the period from 1750-1820 (the Classical period), this article is about the broad span of time from roughly the 11th century to the present day, which includes the Classical period and various other periods. The central norms of this tradition became codified between 1550 and 1900, which is known as the common practice period. The major time divisions of classical music are as follows: the early music period, which includes the Medieval (500–1400) and the Renaissance (1400–1600) eras; the Common practice period, which includes the Baroque (1600–1750), Classical (1750–1820), and Romantic eras (1804–1910); and the 20th century (1901–2000) which includes the modern (1890–1930) that overlaps from the late 19th-century, the high modern (mid 20th-century), and contemporary or postmodern (1975–2015) eras.

Music video

A music video or song video is a short film integrating a song and imagery, produced for promotional or artistic purposes. Modern music videos are primarily made and used as a marketing device intended to promote the sale of music recordings. There are also cases where songs are used in tie in marketing campaigns that allow them to become more than just a song. Tie ins and merchandising could be used in toys are marketing campaigns for food and other products. Although the origins of music videos date back to musical short films that first appeared in the 1920s, they came into prominence in the 1980s when MTV based their format around the medium. Prior to the 1980s, these works were described by various terms including "illustrated song", "filmed insert", "promotional (promo) film", "promotional clip", "promotional video", "song video", "song clip" or "film clip". Since the creation and increased popularity of YouTube, mainstream artists now promote new music videos by releasing trailers of short promos on the site for their upcoming song and music video. Consequentially, YouTube has been converted into a social media platform for celebrities and artists to market themselves to their fans and audiences.