A waistcoat has a full vertical opening in the front, which fastens with buttons or snaps. Both single-breasted and double-breasted waistcoats exist, regardless of the formality of dress, but single-breasted ones are more common. In a three piece suit, the cloth used matches the jacket and trousers. Waistcoats can also have lapels or revers depending on the style.
Wearing a belt with a waistcoat, and indeed any suit, is not traditional. To give a more comfortable hang to the trousers, the waistcoat instead covers a pair of braces (suspenders in the U.S.) underneath it.
Waiters, sometimes also waitresses, and other people working at white-tie events, to distinguish themselves from guests, sometimes wear gray tie, which consists of the dress coat of white tie (a squarely cut away tailcoat) with the black waistcoat and tie of black tie.