In baseball, when a batter is said to have "struck out," it means they have accumulated three strikes without hitting the ball in play or swinging at a pitch that is deemed within the strike zone. This results in the batter being called out, which is a key part of the game as it can significantly affect the outcome of the inning. A strike can occur when a batter misses a pitched ball, does not swing at a pitch within the strike zone, or hits a foul ball (with some exceptions).