Boxing (sometimes known as pugilism or fist-fight) is a combat sport of prehistoric origin in which two participants (generally) of similar weight fight each other with their fists. There have been many informal forms of boxing throughout the centuries, since getting two people to fight with fists is in essence a fairly primitive sport, but boxing is now generally conducted in a regulated way, typically in a series of one to three-minute intervals called rounds. Victory is achieved if the opponent is knocked down and unable to get up before the referee counts to ten (a Knockout, or KO) or if the opponent is deemed too injured to continue (a Technical Knockout, or TKO). If there is no stoppage of the fight before an agreed number of rounds, a winner is determined either by the referee's decision or by judges' scorecards.In some countries with their own fighting sports, the sport is referred to as "English Boxing" (e.g. in France to contrast with French Boxing). There are numerous different forms of boxing practiced across the world.