Baize is a coarse woollen (or in cheaper variants cotton) cloth.
A mid-17th century English ditty (a short, simple popular song)—much quoted in histories of ale and beer brewing in England—refers to 1525 as the year:
Hops, heresies, bays, and beer;
Came into England all in one year.
Heresies refers to the Protestant Reformation, while bays is the Elizabethan spelling for baize.
Baize is most often used on snooker and billiards tables to cover the slate and cushions, and is often used on other kinds of gaming tables such as those for blackjack, baccarat, craps and other casino games. It is also found as a writing surface, particularly on 19th century pedestal desks.
The surface finish of baize is not very fine (and thus increases friction, perceptibly slowing the balls down, from a player's perspective). Baize is available with and without a perceptible nap. Snooker, in which understanding of the effects of the nap is part of the game, uses the nappy variety, while pool (pocket billiards) and carom billiards use the napless type. Table baize is available in many grades, with pool halls preferring smooth, "fast" worsted woollen baize, while rather more fuzzy, "slow" cloth is commonly used for bar/pub pool.