Music is the arrangement of sound to create some combination of form, harmony, melody, rhythm, or otherwise expressive content. Music is generally agreed to be a cultural universal that is present in all human societies. Definitions of music vary widely in substance and approach. While scholars agree that music is defined by a small number of specific elements, there is no consensus as to what these necessary elements are. Music is often characterized as a highly versatile medium for expressing human creativity. Diverse activities are involved in the creation of music, and are often divided into categories of composition, improvisation, and performance. Music may be performed using a wide variety of musical instruments, including the human voice. It can also be composed, sequenced, or otherwise produced to be indirectly played mechanically or electronically, such as via a music box, barrel organ, or digital audio workstation software on a computer.

Music often plays a key role in social events and religious ceremonies. The techniques of making music are often transmitted as part of a cultural tradition. Music is played in public and private contexts, highlighted at events such as festivals and concerts for various different types of ensembles. Music is used in the production of other media, such as in soundtracks to films, TV shows, operas, and video games.

Listening to music is a common means of entertainment. The culture surrounding music extends into areas of academic study, journalism, philosophy, psychology, and therapy. The music industry includes songwriters, performers, sound engineers, producers, tour organizers, distributors of instruments, accessories, and publishers of sheet music and recordings. Technology facilitating the recording and reproduction of music has historically included sheet music, microphones, phonographs, and tape machines, with playback of digital music being a common use for MP3 players, CD players, and smartphones.

The modern English word music came into use in the 1630s. It descends from Middle English musike, which in turn descends from Old French musique, then Latin mūsica—and ultimately from Ancient Greek mousiké technē (μουσική τέχνη), a phrase meaning "art of the Muses". The Muses were nine deities in Ancient Greek mythology who presided over the arts and sciences. They were included in tales by the earliest Western authors, Homer and Hesiod, and eventually came to be associated with music specifically. Over time, Polyhymnia would reside over music more prominently than the other muses. The Latin word musica was also the originator for both the Spanish música and French musique via spelling and linguistic adjustment, though other European terms were probably loanwords, including the Italian musica, German Musik, Dutch muziek, Norwegian musikk, Polish muzyka and Russian muzïka.

The modern Western world usually defines music as an all-encompassing term used to describe diverse genres, styles, and traditions. This is not the case worldwide, and languages such as modern Indonesian (musik) and Shona (musakazo) have recently adopted words to reflect this universal conception, as they did not have words that fit exactly the Western scope. Before Western contact in East Asia, neither Japan nor China had a single word that encompasses music in a broad sense, but culturally, they often regarded music in such a fashion. The closest word to mean music in Chinese, yue, shares a character with le, meaning joy, and originally referred to all the arts before narrowing in meaning. Africa is too diverse to make firm generalizations, but the musicologist J. H. Kwabena Nketia has emphasized African music's often inseparable connection to dance and speech in general. Some African cultures, such as the Songye people of the Democratic Republic of the Congo and the Tiv people of Nigeria, have a strong and broad conception of 'music' but no corresponding word in their native languages. Other words commonly translated as music often have more specific meanings in their respective cultures: the Hindi word for music, sangita, properly refers to art music, while the many Indigenous languages of the Americas have words for music that refer specifically to song but describe instrumental music regardless. Though the Arabic musiqi can refer to all music, it is usually used for instrumental and metric music, while khandan identifies vocal and improvised music.

It is often debated to what extent the origins of music will ever be understood, and there are competing theories that aim to explain it. Many scholars highlight a relationship between the origin of music and the origin of language, and there is disagreement surrounding whether music developed before, after, or simultaneously with language. A similar source of contention surrounds whether music was the intentional result of natural selection or was a byproduct spandrel of evolution. The earliest influential theory was proposed by Charles Darwin in 1871, who stated that music arose as a form of sexual selection, perhaps via mating calls. Darwin's original perspective has been heavily criticized for its inconsistencies with other sexual selection methods, though many scholars in the 21st century have developed and promoted the theory. Other theories include that music arose to assist in organizing labor, improving long-distance communication, benefiting communication with the divine, assisting in community cohesion or as a defense to scare off predators.

Prehistoric music can only be theorized based on findings from paleolithic archaeology sites. The disputed Divje Babe flute, a perforated cave bear femur, is at least 40,000 years old, though there is considerable debate surrounding whether it is truly a musical instrument or an object formed by animals. The earliest objects whose designations as musical instruments are widely accepted are bone flutes from the Swabian Jura, Germany, namely from the Geissenklösterle, Hohle Fels and Vogelherd caves. Dated to the Aurignacian (of the Upper Paleolithic) and used by Early European modern humans, from all three caves there are eight examples, four made from the wing bones of birds and four from mammoth ivory; three of these are near complete. Three flutes from the Geissenklösterle are dated as the oldest, c. 43,150–39,370 BP.

The earliest material and representational evidence of Egyptian musical instruments dates to the Predynastic period, but the evidence is more securely attested in the Old Kingdom when harps, flutes and double clarinets were played. Percussion instruments, lyres, and lutes were added to orchestras by the Middle Kingdom. Cymbals frequently accompanied music and dance, much as they still do in Egypt today. Egyptian folk music, including the traditional Sufi dhikr rituals, are the closest contemporary music genre to ancient Egyptian music, having preserved many of its features, rhythms and instruments.