Professional bouts are usually much longer than amateur bouts, typically ranging from ten to twelve rounds, though four round fights are common for less experienced fighters or club fighters. There are also some two and three round professional bouts, especially in Australia. Through the early twentieth century, it was common for fights to have unlimited rounds, ending only when one fighter quit, benefiting high-energy fighters like Jack Dempsey. Fifteen rounds remained the internationally recognized limit for championship fights for most of the twentieth century until the early 1980s, when the death of boxer Duk Koo Kim reduced the limit to twelve.
Headgear is not permitted in professional bouts, and boxers are generally allowed to take much more punishment before a fight is halted. At any time, however, the referee may stop the contest if he believes that one participant cannot defend himself due to injury. In that case, the other participant is awarded a technical knockout win. A technical knockout would also be awarded if a fighter lands a punch that opens a cut on the opponent, and the opponent is later deemed not fit to continue by a doctor because of the cut. For this reason, fighters often employ cutmen, whose job is to treat cuts between rounds so that the boxer is able to continue despite the cut. If a boxer simply quits fighting, or if his corner stops the fight, then the winning boxer is also awarded a technical knockout victory. In contrast with amateur boxing, professional male boxers have to be bare chested.
Amateur boxing may be found at the collegiate level, at the Olympic Games and Commonwealth Games, and in many other venues sanctioned by amateur boxing associations. Amateur boxing has a point scoring system that measures the number of clean blows landed rather than physical damage. Bouts consist of three rounds of three minutes in the Olympic and Commonwealth Games, and three rounds of two minutes in a national ABA (Amateur Boxing Association) bout, each with a one-minute interval between rounds.
Competitors wear protective headgear and gloves with a white strip across the knuckle. A punch is considered a scoring punch only when the boxers connect with the white portion of the gloves. Each punch that lands cleanly on the head or torso with sufficient force is awarded a point. A referee monitors the fight to ensure that competitors use only legal blows. A belt worn over the torso represents the lower limit of punches – any boxer repeatedly landing low blows (below the belt) is disqualified. Referees also ensure that the boxers don't use holding tactics to prevent the opponent from swinging. If this occurs, the referee separates the opponents and orders them to continue boxing. Repeated holding can result in a boxer being penalized or ultimately disqualified. Referees will stop the bout if a boxer is seriously injured, if one boxer is significantly dominating the other or if the score is severely imbalanced. Amateur bouts which end this way may be noted as "RSC" (referee stopped contest) with notations for an outclassed opponent (RSCO), outscored opponent (RSCOS), injury (RSCI) or head injury (RSCH).