A K.O. (Knockout) occurs in combat sports, such as boxing and mixed martial arts, when a fighter is rendered unable to continue the match. This typically happens when a competitor is struck with a powerful blow that causes them to fall to the ground and remain there, often unable to rise before the referee counts to ten. In a K.O. situation, the fight ends immediately, and the fighter who delivered the knockout is declared the winner. K.O.s are a significant aspect of these sports, showcasing a fighter's skill and power while also emphasizing the importance of safety and sportsmanship.