A nightclub (often simply club, particularly in the UK) is any entertainment venue which does its primary business after dark. Many times, it is associated with music (either with live musicians or music mixed by a DJ,) which can range from jazz or blues to electronic music styles such as drum and bass, house, trance or techno. In addition, the term is sometimes used to describe adult-entertainment venues.

In the U.S. the repeal of Prohibition in February 1933 sparked the revival of nightclubs, which had gone underground, as 'speakeasies. In New York City, three famous midtown nightclubs from the 'Golden Age' were the Stork Club, El Morocco, and the Copacabana, while uptown in Harlem the Cotton Club was king. The first rock and roll generation didn't favor nightclubs, but the club returned in the 1970s as the "disco", from the French discothèque (although by the early 2000s, the term "disco" had largely fallen out of favor). Two early discos in New York were 'Le Club' and 'Regine's'.

Gatherings in nightclubs which primarily involve music mixed by a DJ involve dancing and in most cases alcohol. Illegal use of recreational drugs such as ecstasy is commonplace in many modern clubs.

Often there are light-effects such as many colorful lights, light going on and off, moving light beams, etc. One common item is a disco ball: a rotating football-sized ball at the ceiling, covered with many small flat mirrors, with a light beam directed on it; the reflections form a multitude of moving light spots on the floor and on the people.

Clubs are oftened advertised by the handing out of flyers on the street, in record shops, and at other clubs and events, they are often highly decorative and eye-catching.

Notable nightclubs include:

See also: rave