Ice hockey rules define the parameters of the sport of ice hockey. The sport is governed by several organizations including the International Ice Hockey Federation (IIHF), the National Hockey League (NHL), Hockey Canada, USA Hockey and others. The rules define the size of the hockey rink where a game is played, the playing and safety equipment, the game definition, including time of play and whether tie-breaking methods are used and the actual playing rules themselves. The IIHF rule book is used in both amateur and professional leagues world-wide. The NHL's rule book is the basis for the rule books of most North American professional leagues. The IIHF, amateur and NHL rules evolved separately from amateur and professional Canadian ice hockey rules of the early 1900s.