A personal foul is charged to a player for illegal contact during the game. Depending on the situation and competition rules, it can lead to free throws, a change of possession or foul trouble. Repeated fouls can also restrict a player's minutes and defensive aggression.

Personal fouls directly affect defensive effectiveness and player management. A player in foul trouble may defend less aggressively or spend more time on the bench. Team foul totals also help explain how often the opposition reaches the free-throw line.

A centre commits a fourth foul early in the third quarter. Even if the player has defended well, the coach may use the bench to reduce the risk of another quick foul.