Billiards is a game consisting of billiard balls, cues, and a particular table (usually slate covered in felt, twice as long as it is wide - e.g. 4'X8', 4.5'X9', 5'X10'. There are numerous games that have the different goals of winning (e.g. making a certain number of balls, or a certain ball). Games are played by hitting a "cue ball" into an object ball with the cue stick.
In 1865, John Wesley Hyatt patented a composition material resembling ivory for a billiard ball (US50359), winning $10,000 prize from Phelan and Collender of New York City for the best substitute for ivory. This was the first U.S. patent for billiard balls.
Some billiard games by type of table: