Rules of snooker

Snooker is a cue sport that is played on a baize-covered billiard table with pockets in each of the four corners and in the middle of each of the long side cushions. It is played using a cue and snooker balls: one white cue ball, 15 red balls worth one point each (the game is sometimes played with fewer red balls, commonly 6 or 10), and six balls of different colours: yellow (2 points), green (3), brown (4), blue (5), pink (6), black (7). A player (or team) wins a frame (individual game) of snooker by scoring more points than the opponent(s), using the cue ball to pot the red and coloured object balls. A player (or team) wins a match when they have achieved the best-of score from a pre-determined number of frames. The number of frames is always odd so as to prevent a tie or a draw.

Snooker is played on a rectangular snooker table with six pockets, one at each corner and one in the middle of each long side. The table usually has a slate base, covered in green baize. A baulk line is drawn across the width of the table, 29 inches (74 cm) from the cushion at one end; these two latter items are respectively designated as the baulk cushion and baulk end. A semicircle of radius 11+1⁄2 inches (29 cm), called the "D", is drawn behind this line, with its centre on the midpoint. The cushion at the other end of the table is known as the top cushion.

A regulation (full-size) table is 12 ft × 6 ft (3.7 m × 1.8 m); because of the large size of these tables, smaller tables are common in homes, pubs and other places where space is limited. These are often around 6 feet (1.8 m) in length, with all the dimensions and markings scaled down accordingly. The balls used are sometimes also scaled down, and/or reduced in number (in the case of the reds) by omitting the longest row of balls in the rack.

Snooker balls, like Billiard balls, are typically made of phenolic resin, and are smaller than American pool balls. Regulation snooker balls (which are specified in metric units) are nominally 52.5 mm (approximately 2+1⁄15 inches) in diameter, though many sets are actually manufactured at 52.4 mm (about 2+1⁄16 in). No weight for the balls is specified in the rules, only that the weight of any two balls should not differ by more than 0.5 g. Some recreational sets (which are usually not measured metrically) are 2+1⁄8 in (about 54 mm) up to as large as pool balls, at 2+1⁄4 in (about 57.2 mm); larger ball size requires wider pocket openings. Miniature sets also exist, for half-size home tables. There are fifteen red balls, six "colour" balls (yellow, green, brown, blue, pink, and black), and one white cue ball. Usually none of the balls are numbered, though the six colour balls often are in the US, where they are easily mistaken at first glance for pool balls (the design is similar, but the numbering does not match pool's scheme).

At the beginning of a frame, the balls are set up in the arrangement shown in the illustration. The six colours (a term referring to all balls except the white and the reds) are placed on their own spots. On the baulk line, looking up the table from the baulk end, the green ball is located where the "D" meets the line on the left, the brown ball in the middle of the line, and the yellow ball where the "D" meets the line on the right. This order is often remembered using the mnemonic God Bless You, the first letter of each word being the first letter of the three colours (Green, Brown, Yellow). The blue ball rests at the exact centre of the table, while the pink is placed midway between it and the top cushion. The red balls are arranged in a tightly-packed triangle behind the pink, with the apex as close as possible to the pink but not touching it. Finally, the black ball is placed on a spot 12+3⁄4 in (324 mm) from the top cushion, centred from left to right so that the brown, blue, pink, and black balls all sit on an imaginary line that bisects the table along its length.

The objective of the game of snooker is to strike the white cue ball with a cue so that it strikes the object balls in turn and causes them to fall into one of the six pockets, called potting. Points are scored for potting balls legally, in accordance with the rules described below, or in the event of a foul committed by the opponent. The player who scores more points wins the frame, and the first player to win a set number of frames wins the match.

A match usually consists of a fixed, odd number of frames. A frame begins with setting up the balls as described above. A frame ends when all balls are potted, or when one of the players concedes defeat due to being too far behind on points to tie or beat the opponent's score.

A match ends when one player has won enough frames to make it impossible for the other player to catch up. For example, in a match of 19 frames, the first player to win 10 is the victor.