In basketball and other such timed sports, a buzzer beater is a shot that is taken before the game clock of a quarter, a half (if the half is the second one, then, a game), or an overtime period expires but does not go in the basket until after the clock expires and the buzzer sounds hence the name "buzzer beater". The concept normally applies to baskets that beat an end-of-quarter/2nd-half/overtime buzzer but is sometimes applied to shots that beat the shot clock buzzer.

Officials in the National Collegiate Athletic Association, National Basketball Association, Women's National Basketball Association, Serie A (Italy), and the Euroleague (Final Four series only, effective 2006) are required to use instant replay to assess whether a shot made at the end of a period was in fact released before the game clock expired. Since 2002, the NBA also has mandated LED light strips along the edges of the backboard and the edge of the scorer's table for the purposes of identifying the end of a period.