A nightclub (often dance club or club, particularly here in the UK) is an entertainment venue which does its primary business after dark.
Nightclubs are always associated with music and have a dance floor, however small: a drinking establishment without music is a saloon or bar, a pub or a tavern. Though a nightclub may have a floor show or other entertainment unsuitable for minors, the music, dancing and socializing of a night club are secondary in a "strip joint". Music may be live or mixed by a DJ, and can range from jazz or blues to electronic music styles such as drum and bass, house, trance or techno.
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 featuring electronic dance music. 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.
Nightclubs often feature lighting and other effects: flashing lights of many colors, moving light beams and smoke machines. 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.