In basketball, a block or blocked shot occurs when a defensive player legally deflects a field goal attempt from an offensive player to prevent a score. The defender is not allowed to make contact with the offensive player's hand or a foul is called. In order to be legal, the block must occur while the shot is traveling upward or at its apex. A deflected field goal that is made does not count as a blocked shot and simply counts as a successful field goal attempt for shooter plus the points awarded to the shooting team. For the shooter, a blocked shot is counted as a missed field goal attempt. Also, on a shooting foul, a blocked shot cannot be awarded or counted, even if the player who deflected the field goal attempt is different from the player who committed the foul. If the ball is heading downward when the defender hits it, it is ruled as goaltending and counts as a made basket. Goaltending is also called if the block is made after the ball bounces on the backboard.

Basketball is a team sport in which two teams, most commonly of five players each, opposing one another on a rectangular court, compete with the primary objective of shooting a basketball through the defender's hoop, while preventing the opposing team from shooting through their own hoop. A field goal is worth two points, unless made from behind the three-point line, when it is worth three. After a foul, timed play stops and the player fouled or designated to shoot a technical foul is given one, two or three one-point free throws. The team with the most points at the end of the game wins, but if regulation play expires with the score tied, an additional period of play (overtime) is mandated.