A shot clock is used in some sports to quicken the pace of the game. It is normally associated with basketball, but is also used in snooker, pro lacrosse, water polo, and korfball.

In basketball, the shot clock is a timer designed to increase the game's pace (and score). The offensive team must attempt a field goal before the shot clock expires, and the ball must then either touch the rim or enter the basket, or the offensive team will be assessed a violation resulting in a turnover. However, if the ball leaves the hand of the player before the shot clock goes off and makes it or hits the rim, it is not a violation.

The National Basketball Association had problems attracting fans (and TV coverage) before its inception. This was due to teams running out the clock once they were leading in a game; without the shot clock, teams passed the ball nearly endlessly without penalty. If one team chose to stall, the other team (especially if behind) would often commit fouls to get the ball back following the free throw. Very low-scoring games with many fouls were common, boring fans. The most extreme case occurred on November 22, 1950, when the Fort Wayne Pistons defeated the Minneapolis Lakers by a record-low score of 19-18, including 3-1 in the fourth quarter. The Pistons held the ball for minutes at a time without shooting to limit the impact of the Lakers' dominant George Mikan. The Pistons attempted 13 shots in the game. The St. Paul Dispatch wrote "[The Pistons] gave pro basketball a great black eye." NBA President Maurice Podoloff said, "In our game, with the number of stars we have, we of necessity run up big scores." A few weeks later, the Rochester Royals and Indianapolis Olympians played a six-overtime game with only one shot in each overtime. The NBA tried several rule changes in the early 1950s to speed up the game and reduce fouls before eventually adopting the shot clock.

Ronald Antonio "Ronnie" O'Sullivan (born 5 December 1975) is an English professional snooker player known for his rapid playing style, and is nicknamed "The Rocket". He has been World Champion on four occasions (2001, 2004, 2008 and 2012) and, with career earnings of over £6 million is second after Stephen Hendry on snooker's all-time prize-money list. O'Sullivan has been the world's no. 1 player on five occasions, and has won a total of 24 ranking titles. He is second, again behind Hendry, on the list of players making the most competitive century breaks, with a total of 678. O'Sullivan has compiled 11 maximum breaks in professional competition, a record which he shares with Hendry. He also holds the record for the fastest maximum break, at 5 minutes 20 seconds.

O'Sullivan is considered by many fans, critics and professionals, including fellow multiple-World Championship winners Hendry and Steve Davis, as the most naturally talented player in the history of the game. He has, however, been involved in a number of controversial incidents during his career.