Periods and overtime

A game consists of three periods of twenty minutes each, the clock running only when the puck is in play. The teams change ends for the second period, again for the third period, and again at the start of each overtime played. Recreational leagues and children's leagues often play shorter games, generally with three shorter periods of play.
Various procedures are used if a game is tied. In tournament play, as well as in the NHL playoffs, North Americans favour sudden death overtime, in which the teams continue to play 20 minute periods until a goal is scored. Up until the 1999-2000 season regular season NHL games were settled with a single 5 minute sudden death period with 5 players (plus a goalie) per side, with the winner awarded 2 points in the standings and the loser 0 points. In the event of a tie (if the OT was scoreless), each team was awarded 1 point. From 1999-2000 until 2003-04 the National Hockey League decided ties by playing a single five-minute sudden death overtime period with each team having 4 players (plus a goalie) per side to "open-up" the game. In the event of a tie, each team would still receive 1 point in the standings but in the event of a victory the winning team would be awarded 2 points in the standings and the losing team 1 point. The only exception to this rule is if a team opts to pull their goalie in exchange for an extra skater during overtime and is subsequently scored upon (an 'Empty Net' goal), in which case the losing team receives no points for the overtime loss. International play and several North American professional leagues, including the NHL (in the regular season), now use an overtime period followed by a penalty shootout. If the score remains tied after an extra overtime period, the subsequent shootout consists of three players from each team taking penalty shots. After these six total shots, the team with the most goals is awarded the victory. If the score is still tied, the shootout then proceeds to a sudden death (actually sudden victory) format. Regardless of the number of goals scored during the shootout by either team, the final score recorded will award the winning team one more goal than the score at the end of regulation time. In the NHL if a game is decided by a shootout the winning team is awarded 2 points in the standings and the losing team is awarded 1. Ties no longer occur in the NHL.