Snooker is a cue sport played on a 6 foot by 12-foot rectangular billiard table covered with a green cloth often referred to as the baize. There are six pockets, one in each corner and one in the middle of each of the longest sides.

The game is played with 22 unmarked balls: 15 red balls, six coloured balls and one white ball known as the “cue ball.” At the start of the game (often called a “frame”) the red balls are racked into a tightly packed equilateral triangle and the six coloured balls are positioned at designated spots on the table.

Starting with the cue ball inside the “D” the first player executes a break-off shot by striking the cue ball with the tip of their cue, aiming to hit any of the red balls in the triangular pack. The tip of the cue must only contact the cue ball and is never used for striking any of the reds or colours directly. The players then take alternating turns playing shots with the aim of striking a red ball and sending it into a pocket; this is alternatively referred to as potting or pocketing. The successful potting of a red ball is worth one point. At the end of each shot, the cue ball remains in the position where it has come to rest. When a red ball has been potted, the player must then pot one of the six coloured balls of their choice. If successful, the value of the potted colour is added to the player's score. Red balls are never re-spotted on the table but the coloured balls are returned to their designated spots as long as reds remain on the table. Once the coloured ball is re-spotted, the player must then pot another red ball followed by another colour, and so on. Once all 15 reds and a subsequent colour have been potted, 30 shots in total, the player then will pocket the six colours in ascending order of their point value: yellow, green, brown, blue, pink and black. At this stage each colour remains in the pocket after being potted.

The points a player accumulates by potting successive object balls are called a “break.” If a player successfully pots all the balls on the table it is referred to as a “total clearance.” A 147 (spoken as one-four-seven) is a special type of “total clearance” achieved by potting all 15 reds with blacks for a total of 120, followed by all six colors in sequence for an additional 27 points. It is the “maximum break” or highest possible score in a single visit to the table in normal circumstances. Overall, a 147 break in snooker is an exceptional achievement.

A player remains at the table accumulating points for each successive ball pocketed until all the balls have been potted or the player fails to pot the an object ball and/or commits a foul such as playing a shot which results in the pocketing of the cue ball—at which point the opponent comes to the table to start the next turn. If the cue ball has been pocketed it is given “in hand” and the player coming to the table may position it anywhere on the lines of, or within, the “D” to begin their turn.

When the final ball is potted, the player with the most points wins the frame. If there are not enough points remaining on the table for a player to win the frame, that player may offer to concede the frame while at the table but not while their opponent is still at the table. However, players will often play on even when there are not enough points available for them to win through potting balls because they can also score points by forcing their opponent into making foul shots. This is most effectively done by laying “snookers.” These are shots designed to make playing a legal shot harder, such as by leaving another ball between the cue ball and the object ball as an obstruction.

The cue ball may contact an object ball directly or it can be made to bounce off one or more cushions before hitting the object ball but it must hit the object ball first before any other ball. Failure to make contact with the ball-on, whether it is a red or one of the six colours, constitutes a foul and results in points being awarded to the opponent. Fouls are also committed when the ball-on is a coloured ball and the player accidentally pockets one of the other colours or a red; however, when the ball-on is a red, and the player has contacted the ball-on legally but the trajectory of that red or the cue-ball sends one of the other reds into the pocket, this remains a legal shot and the player is awarded one point. A player can also commit a foul shot when any shot played results in the cue ball ending up in a pocket. In either case, the value of the points awarded to the opponent is dictated by the value of the ball that the player was trying to hit and missed or the value of the ball that was pocketed by mistake, whichever is the greater.

If the scores are equal when all of the object balls have been potted, the black is used as a tiebreaker. This situation is called a “re-spotted black.” The black ball is returned to its designated spot and the player chosen to play first takes the cue ball “in hand” to start the tiebreak. The game continues until one of the players either pots the black ball to win the frame, or commits a foul losing 7 points to his opponent and thereby losing the frame.
The global governing body for professional snooker is the World Professional Billiards and Snooker Association (WPBSA). The WPBSA is responsible for the governance of the Official Rules of Snooker and Billiards. The rules are available to download for free at the WPBSA site (link to https://wpbsa.com/rules/) or you can order a physical copy by contacting the WPBSA directly (link to https://wpbsa.com/about-us/contact/)