A coat is a long garment worn by both men and women, for warmth or fashion. Coats typically have long sleeves and are open down the front, closing by means of buttons, zippers, hook-and-loop fasteners, toggles, a belt, or a combination of some of these. Other possible features include collars and shoulder straps.

The Persians, based in what is now Iran, introduced two garments to the history of clothing: trousers and seamed fitted coats.

Coat is one of the earliest clothing category words in English, attested as far back as the early Middle Ages. (See also Clothing terminology.)

An early use of coat in English is coat of mail (chainmail), a tunic-like garment of metal rings, usually knee- or mid-calf length.

The medieval and renaissance coat (generally spelled cote by costume historians) is a midlength, sleeved men's outer garment, fitted to the waist and buttoned up the front, with a full skirt in its essentials, not unlike the modern coat.

By the eighteenth century, overcoats had begun to supplant capes and cloaks as outer wear, and by the mid-twentieth century the terms jacket and coat became confused for recent styles; the difference in use is still maintained for older garments.