A TKO, or technical knockout, is a fight-ending criterion in several full-contact combat sports, such as boxing, kickboxing, muay thai, mixed martial arts, karate, and some forms of taekwondo. It is declared when the referee decides during a round that a fighter cannot safely continue the match for any reason, or when a fighter is knocked down three times in one round. In amateur boxing, a TKO is declared when a fighter is knocked down four times in an entire match. In MMA bouts, the referee may declare a TKO if a fighter cannot intelligently defend themselves while being repeatedly struck. A TKO can also occur if a fighter decides that they are no longer able to take part in the fight, or if one of their ringside team decides to withdraw their fighter from any further action. In contrast, a KO, or knockout, is usually awarded when one participant falls to the canvas and is unable to rise to their feet within a specified period of time, typically because of exhaustion, pain, disorientation, or unconsciousness.