A bar (also called a pub or tavern) is a business that serves drinks, especially alcoholic beverages such as beer, liquor, and mixed drinks, for consumption on the premises. Bars provide stools or chairs for the patrons along tables or raised counters. Some bars have entertainment on a stage, such as a live band, comedians, go-go dancers, a floor show or various other forms of entertainment. Bars that are part of hotels are sometimes called long bars or hotel lounges.

The term "bar" is derived from the specialized counter on which drinks are served and is a synecdoche applied to the whole of the drinking establishment. The "back bar" or "gantry" is a set of shelves of glasses and bottles behind that counter. In some bars, the gantry is elaborately decorated with woodwork, etched glass, mirrors, and neon bar signs. When food is served elsewhere in the establishment, it may also be ordered and eaten at the bar.

There are many types of bars, which can be categorized according to the types of entertainment provided at the bar and by their clientèle.

Bars categorized by the type of entertainment or activities offered at the bar include: Sports bars, where sports fans watch games on large-screen televisions; salsa bars, where patrons dance to Latin salsa music; and dance bars, which have a modest-sized dance floor where patrons dance to recorded music.

Bars categorized by the clientele who come to the bar include: biker bars, which are bars frequented by motorcycle enthusiasts, and in some regions, motorcycle gang members; cop bars, where off-duty law enforcement agents gather; and singles bars where (mostly) unmarried people of both genders can socialize and meet.