Disco is a genre of dance music. Its popularity peaked during the middle to late 1970s. It had its roots in clubs that catered to African American, gay, psychedelic and other communities in New York City and Philadelphia during the late 1960s and early 1970s. Disco was used as a reaction by New York City's gays as well as blacks, Latinos and heterosexuals against both the domination of rock music and the demonisation of dance music by the counterculture during this period. Women embraced disco as well, and the music eventually expanded to several other popular groups of the time. In what is considered a forerunner to disco style clubs, in February 1970, the New York City DJ David Mancuso opened The Loft, a members-only private dance club set in his own home. Allmusic claims some have argued that Isaac Hayes and Barry White were playing what would be called disco music as early as 1971. According to the music guide there is disagreement as to what the first disco song was. Claims have been made for Manu Dibango's "Soul Makossa" (1972), Jerry Butler's "One Night Affair" (1972), the Hues Corporation's "Rock the Boat" (1974) and George McCrae's "Rock Your Baby" (1974). The first article about disco was written in September 1973 by Vince Aletti for Rolling Stone Magazine. In 1974 New York City's WPIX-FM premiered the first disco radio show.

Musical influences include funk, Latin and soul music. The disco sound has soaring, often reverberated vocals over a steady "four-on-the-floor" beat, an eighth note (quaver) or sixteenth note (semi-quaver) hi-hat pattern with an open hi-hat on the off-beat, and a prominent, syncopated electric bass line sometimes consisting of octaves. The Fender Jazz Bass is often associated with disco bass lines, because the instrument itself has a very prominent 'voice' in the musical mix. In most disco tracks, strings, horns, electric pianos, and electric guitars create a lush background sound. Orchestral instruments such as the flute are often used for solo melodies, and unlike in rock, lead guitar is rarely used.

Well-known late 1970s disco performers included Donna Summer, The Bee Gees, KC and the Sunshine Band, Chic, and The Jacksons. Summer would become the first well-known and most popular disco artist, giving her the title 'The Queen of Disco', and also played a part in pioneering the electronic sound that later became a part of disco (see below). While performers and singers garnered the lion's share of public attention, the behind-the-scenes producers played an equal, if not more important role in disco, since they often usually wrote the songs and created the innovative sounds and production techniques that were part of the "disco sound". Many non-disco artists recorded disco songs at the height of disco's popularity, and films such as Saturday Night Fever and Thank God It's Friday contributed to disco's rise in mainstream popularity. Because the term "disco" became unfashionable at the start of the 1980s it was replaced by "dance music" and "dance pop" which described music powered by the basic disco beat. In the decades since, dance clubs have remained highly popular, and the disco beat has informed the sound of many of music's biggest stars. Disco has been influential on several dance music genres that have emerged since, such as House, Nu-Disco, Hi-NRG, Italo Disco, Eurodisco, Disco-Funk and Latin Freestyle.