The man's suit of clothes is a set of garments which are crafted from the same cloth. The word suit derives from the French suite, meaning "following", because the trousers and waistcoat follow the jacket's cloth and colour. There have been various styles of suit, the most common of which is the lounge suit, which originated in England for wearing in the country. The other type of suits still worn today are the dinner suit (black tie), which arose as a lounging alternative to dress coats in much the same way as the day lounge suit, and (rarely worn today) the morning suit. This article discusses the lounge suit, which is classified as informal in the hierarchy of dress codes. A business suit is a lounge suit suitable for wearing conducting business.

The variations in design, cut, and cloth, such as two- and three- piece, or single- and double- breasted, determine the social and work suitability of the garment. Often, the man's suit is worn, as is traditional, with a collared shirt and necktie. Until around the 1960s, as with all men's clothes, a hat would have been also worn when the wearer was outdoors. Suits also come with different numbers of pieces: a two-piece suit has a jacket and the trousers; a three piece adds a waistcoat; further pieces might include a matching flat cap.

Originally, as with most clothes, a tailor crafted the suit from his client's selected cloth, a process known as "bespoke". The suit was custom made to the measurements, taste, and style of the man. Since the Industrial Revolution, most suits are mass-produced, and, as such, are sold as ready-to-wear garments (though alteration by a tailor prior to wearing is common). Currently, suits are sold in roughly three ways:

bespoke, in which the garment is custom-made from scratch entirely for the customer, giving the best fit and free choice of fabric;
made to measure, in which a pre-made pattern is modified to fit the customer, and a limited selection of options and fabrics is available;
and finally ready-to-wear, which is least expensive and hence most common.