Cue sports are an assortment of games of skill played with a cue which is used to knock billiard balls around a felt covered billiards table surrounded with rubber cushions.

Historically, the umbrella term was billiards. While that familiar name is still employed by some as a generic label for all such games, the word's usage has splintered into more exclusive competing meanings among certain groups and geographic regions. In the United Kingdom, "billiards" refers exclusively to English billiards, while in the United States it is sometimes used to refer to a particular game or class of games, or to all cue games in general, depending upon dialect and context.

There are three major subdivisions of games within cue sports:

• Carom billiards, referring to games played on tables without pockets, including among others balkline and straight rail, cushion caroms, three-cushion billiards and artistic billiards
• Pocket billiards (or "pool") generally played on a table with six pockets, including among others eight-ball (the world's most widely played cue sport), nine-ball, straight pool, one-pocket and bank pool
• Snooker, which while technically a pocket billiards game, is generally classified separately based on its historic divergence from other games, as well as a separate culture and terminology that characterize its play.

More obscurely, there are games that make use of obstacles and targets, and table-top games played with disks instead of balls.

Billiards has a long and rich history stretching from its inception in the 15th century; to the wrapping of the body of Mary, Queen of Scots in her billiard table cover in 1586; through its many mentions in the works of Shakespeare, including the famous line "let us to billiards" in Antony and Cleopatra (1606–07); to the dome on Thomas Jefferson's home Monticello, which conceals a billiard room he hid, as billiards was illegal in Virginia at that time; and through the many famous enthusiasts of the sport including, Mozart, Louis XIV of France, Marie Antoinette, Napoleon, Abraham Lincoln, Mark Twain, George Washington, Charles Dickens, George Armstrong Custer, Theodore Roosevelt, Lewis Carroll, W.C. Fields, Babe Ruth, Bob Hope, Jackie Gleason, and countless others.

Cues sports are generally considered to have developed from outdoor stick-and-ball lawn games
related to troco, croquet and golf, and more distantly to the stickless bocce and bowling. The word "billiard" may have evolved from the French word billart, meaning "mace", an implement similar to a golf club, which was the forerunner to the modern cue. The term "cue sports" can be used to encompass the ancestral mace games, and even the modern cueless variants, such as finger pool, for historical reasons.

In addition to the three general subdivisions listed earlier, a now rare obstacle category was prevalent in early times. The obstacle games (see illustration to the right, featuring a croquet-like variant), appear to have been the earliest, and include the obsolete bagatelle and pin pool among many other variations, some with elaborate structures (likely inspirational of miniature golf), and yet others on a sloped table (the ancestors of pinball), up to the relatively recent bumper pool which was popular in the 1970s.

The object of obstacle games varies from avoiding obstructions and traps, to hitting or passing through or into them on purpose to score, to using them strategically to score in some other way, such as by rebounding off them to reach a hole in the table or trapping opponents' balls.

The early croquet-like games eventually led to the development of the carom or carambole billiards category – what most non-US and non-UK speakers mean by the word "billiards". These games, which once completely dominated the cue sports world but have declined markedly in most areas over the last few generations, are games played with three or sometimes four balls, on a table without holes (or obstructions in most cases, five-pins being an exception), in which the goal is generally to strike one object (target) ball with a cue ball, then have the cue ball rebound off of one or more of the cushions and strike a second ball. Variations include three-cushion, straight rail, balkline variants, cushion caroms, Italian five-pins, and four-ball, among others.

Over time, a type of obstacle returned, originally as a hazard and later as a target, in the form of pockets, or holes partly cut into the table bed and partly into the cushions, leading to the rise of pocket billiards, especially "pool" games, popular around the world in forms such as eight-ball, nine-ball, straight pool and one-pocket amongst numerous others. The terms "pool" and "pocket billiards" are now virtually interchangeable, especially in the US. English billiards (what UK speakers almost invariably mean by the word "billiards") is a hybrid carom/pocket game, and as such is likely fairly close to the ancestral original pocket billiards outgrowth from 18th to early 19th century carom games.