A suit, also called a lounge suit, business suit, dress suit, or formal suit, is a set of clothes comprising a suit jacket and trousers of identical textiles generally worn with a collared dress shirt, necktie, and dress shoes. A skirt suit is similar, but with a matching pencil skirt instead of trousers. It is currently considered semi-formal wear or business wear in contemporary Western dress codes; however, when the suit was originally developed it was considered an informal or more casual option compared to the prevailing clothing standards of aristocrats and businessmen. The lounge suit originated in 19th-century Britain as sportswear and British country clothing, which is why it was seen as more casual than citywear at that time, with the roots of the suit coming from early modern Western Europe formal court or military clothes. After replacing the black frock coat in the early 20th century as regular daywear, a sober one-coloured suit became known as a lounge suit.
Suits are offered in different designs and constructions. Cut and cloth, whether two- or three-piece, single- or double-breasted, vary, in addition to various accessories. A two-piece suit has a jacket and trousers; a three-piece suit adds a waistcoat. Hats were almost always worn outdoors (and sometimes indoors) with all men's clothes until the counterculture of the 1960s in Western culture. Informal suits have been traditionally worn with a fedora, a trilby, or a flat cap. Other accessories include handkerchief, suspenders or belt, watch, and jewelry.