Boxing, also called prizefighting (when referring to professional boxing), the sweet science (a common nickname among fans) or the gentleman's sport (used mainly in England), is a sport and martial art in which two participants of similar weight classification fight each other with their fists in a series of one to three-minute intervals called "rounds". In both Olympic and professional divisions, the combatants (called boxers or fighters) avoid their opponent's punches while trying to land punches of their own. Points are awarded for clean, solid blows to the legal area on the front of the opponent's body above the waistline, with hits to the head and torso being especially valuable.