Rules

The majority of ice hockey around the world is played under the umbrella of three organizations, Hockey Canada, USA Hockey, and the International Ice Hockey Federation, each with their own set of rules. Hockey Canada and USA Hockey rulebooks are used in most amateur hockey in North America, and the IIHF rulebook is used in both amateur and professional leagues.

The National Hockey League has its own rulebook, from which the rulebooks of most North American professional leagues are derived. United States high school leagues use the National Federation of State High School Associations rulebook, and varsity college hockey is governed by the National Collegiate Athletic Association's rules.

These six rules organizations, in addition to their own meetings, gather at a conference, and rule changes significant to game play have traditionally been made "across the board." However, recently, changes have been made at the amateur hockey levels to improve game play, while changes at professional levels have been made to make the game more exciting to spectators.

Hockey Canada and USA Hockey's rulebooks differ primarily in technical matters such as the severity of penalties handed out for various fouls. IIHF rules differ a bit more due to the differences in the dimensions of North American hockey rinks from those in the rest of the world (More recently, the IIHF has considered going to the North American dimensions as the intent of increased offense has been statistically debated). In recent times, both USA Hockey and Hockey Canada have been trying to make their rules more similar to the international rules. The merits of this move toward a more standardized rulebook, however, are debated in amateur hockey circles.

The NHL is very different since they evolved separately from the amateur rules. In recent years, the low scores of NHL games have prompted the league to debate a wide variety of rule change proposals including enlarging the size of the goal, widening the blue and red lines to create a larger offensive zone, restricting where goaltenders can handle the puck, breaking ties with a penalty shot shootout, and eliminating the two-line pass rule, which does not exist in international and most amateur rulebooks.

While the National Hockey League (NHL) follows the general rules of ice hockey, it differs slightly from those used in international games organized by the International Ice Hockey Federation such as the Olympics.

Game timing
In the National Hockey League, between stoppages of play, teams have 18 seconds (5 seconds for the visiting team, 8 seconds for the home team, 5 seconds to line up at the faceoff location) to substitute their players, except during TV timeouts. TV timeouts are two minutes long, and occur three times per period: during normal game stoppages after the 6, 10, and 14 minute marks of the period, unless there is a power play, a goal has just been scored, or the stoppage was as a result of an icing. Each team may also take one 30 second time-out, which may only be taken during a normal stoppage of play.

Hockey rink
The hockey rink is an ice rink which is rectangular with rounded corners and surrounded by a wall, usually called the "boards". It measures 200 feet (60.96 m) long by 85 feet (25.91 m) wide in the NHL, whereas international standards call for a rink measuring 60 metres (196.9 ft) to 61 metres (200.1 ft) long by 29 metres (95.1 ft) to 30 metres (98.4 ft) wide. The center line divides the ice in half lengthwise. The center line is used to judge icing violations. There are two blue lines that divide the rink roughly into thirds. They divide the ice into zones. Near each end of the rink, there is a thin red goal line spanning the width of the ice. It is used to judge goals and icing calls. The "Blue" and "Red" Lines are 1 foot in width. All other markings on the ice (goal lines, circles, etc.) are 2 inches in width.

New in the 2005–06 season, after testing in the American Hockey League, is a trapezoid behind each goalie net. The goalie can only play the puck within that area or in front of the goal line. If he plays the puck behind the goal line and not in the trapezoid, a 2 minute minor penalty for delay of game will be assessed by the referees. This rule is widely referred to as the "Brodeur rule," after New Jersey Devils goalie Martin Brodeur, whose puckhandling behind the net is believed to be the cause for the rule.[1] [2]

Scoring and winning
A goal is scored when the puck completely crosses the goal line and enters the net. A goal may be disallowed under the following circumstances: When a game is tied at the end of regulation, it goes into a 4-on-4 overtime. When there is a goal during it, the game ends and the team that made that goal wins. If there is no scoring in the overtime, it will go into a 3-on-3 shootout. This sequence ends when one team mathematically has more shootout goals than the other, thus winning the game. If neither team emerges victorious, the shootout continues one frame at a time until one team scores and the other does not, in which case the team who scores, wins.
 * the scoring team takes a penalty (except if the other team accidentally puts the puck into its own net untouched by the team to be penalized);
 * the puck is directed in by an attacker's high stick (above the crossbar), or when the puck has been directed, batted or thrown into the net by an attacking player other than with a stick (angling one's skate is allowed).
 * goaltender interference (which can also result in a penalty)
 * the puck goes in after the Referee intends to stop play (i.e. for the goalcrease after the net has been dislodged). This results in an immediate stoppage of play.
 * the puck deflects off a referee or linesman and goes directly into the goal.

A team that loses a game in overtime or the shootout will receive one point in the standings; the awarding of game points to losing teams is a point of debate among fans and the media.

Shootouts are not used in the playoffs. If a playoff game is tied at the end of the regulation, the game instead enters a twenty-minute 5-on-5 sudden-death overtime. The game continues indefinitely in this format until a goal is scored; the team that scores this goal immediately wins the game. Additional 20-minute overtime periods are played as necessary until the winning goal is scored. In the Playoffs teams switch ends before every Overtime period. In the Regular Season teams do not switch ends after the third period and defend the same goal in overtime and the shootout as they did in the first and third periods.

Offside
In ice hockey, play is said to be offside if a player on the attacking team enters the offensive zone before the puck (unless the defensive team brings the puck into their own zone). A violation occurs when an offside player touches the puck. If a player crosses the line ahead of the puck but his team is not in possession of it, the linesman will raise his arm to signal a delayed offside; when all players from the offside team leave their offensive zone ("tag up" in the neutral zone) the linesman washes out the delayed call. When an offside violation occurs, the linesman blows the play dead, and a faceoff is conducted in the neutral zone. During the 2004-05 lockout, the league removed the "offside pass" or "two-line pass" rule, which required a stoppage in play if a pass originating from inside a team's defending zone was completed on the offensive side of the center line, unless the puck crossed the line before the player. The removal of the two-line offside was one of several rule changes intended to increase overall scoring, which had been in decline since the early 1990s. The only time a player may precede the puck into the attack zone with the puck behind in the neutral zone is if none of his teammates are in the attack zone and the player with the puck has control of the puck in the estimation of the linesman(short-sticking/spin-o-rama)

Icing
Icing occurs when a player shoots the puck across both the center line and the opposing team's goal line without the puck going through the goal crease. When icing occurs, a linesman stops play if a defending player (other than the goaltender) touches the puck before an attacking player is able to. Play is resumed with a faceoff in the defending zone of the team that committed the infraction. Icing is not enforced for a team that is short-handed. If the goaltender makes a move from his net to play the puck, the icing is immediately waved off (in contrast to minor league and international hockey, where the goaltender must play the puck for it to be waved off). Icing can also be waved off if, in the officials' opinion, the defending team had a viable opportunity to play the puck before crossing the goal line. After an icing, a TV timeout cannot be called.

According to the rules following the 2004–2005 lockout, if a team is guilty of icing the puck, it is not allowed to make a line change before the following faceoff.

Penalties
A penalty is a punishment for infractions of the rules. A referee makes most penalty calls while the linesmen may call only obvious technical infractions such as too many men on the ice. In the NHL, the linesman may also call major intent-to-injure penalties that the referee may have missed.

During a penalty, the player who committed the infraction is sent to the penalty box. Small infractions are deemed minor penalties, and the player is kept off the ice for two minutes of gameplay. More dangerous infractions, such as fighting, are deemed major penalties and have a duration of five minutes. The penalized team cannot replace the player on the ice and is thus shorthanded for the duration of the penalty. Normally, hockey teams have five skaters (plus the goaltender) on the ice. If a minor or major penalty is called, play becomes "five-on-four" - five skaters versus four skaters.

This situation is called a power play for the non-offending team and a penalty kill for the offending team. A team is far more likely to score on a power play than during normal play. If the penalized team is scored on during a minor penalty, the penalty immediately terminates. Unlike minor penalties, major penalties must be served to their full completion, regardless of number of goals scored during the power play. When a penalty is about to be called, an official will raise his arm to signal what is referred to as a "delayed penalty". Play will continue until the offending team touches the puck, at which point, the official will blow the play dead and assess the penalty. Because of this, the offending team cannot score a goal themselves during a delayed penalty. This usually results in the opposing team replacing their goalie with an extra forward until the offending team touches the puck, since the offending team cannot score on the empty net by touching the puck.

However, the offended team is not completely immune to being scored on. Own goals, while rare, do happen, even in the NHL. For example: There are exceptions to the rule where a team cannot replace a player on the ice after a penalty: mutual majors for fighting, where there are two participants in a fight, will result in each person receiving five minutes, but the penalties will not affect the on-ice strength of either team (play remains five-on-five), unless a player is deemed to be the instigator of the fight, in which case that player will receive an additional two-minute minor. There are also "coincidental" minors in which the penalties called against both teams are simultaneous and equal in length, so that neither team receives a power play.
 * In the November 24, 2008 New York Islanders - Montreal Canadiens game, when the referee was about to call a penalty against New York, Montreal Canadiens goaltender Carey Price headed back to the bench for an extra forward. At that moment, Canadiens defenseman Ryan O'Byrne, not noticing the delayed penalty and the empty net, attempted to pass the puck to his (now-missing) goaltender. Instead, the puck landed in the net and a goal was awarded to the Islanders.
 * In the March 21, 2009 game between the Vancouver Canucks and the Phoenix Coyotes, Phoenix scored an empty-net goal during a delayed penalty against the Coyotes' Viktor Tikhonov. In an attempt to take possession and thus stop play, Tikhonov poke-checked Vancouver's Henrik Sedin near the Vancouver blue line. Since Tikhonov only ever touched Sedin's stick, and not the puck, play continued, even though the puck was now headed straight for Vancouver's goal. Sedin's teammate Shane O'Brien skated after the errant puck, but to no avail. Both the puck and O'Brien landed in the net, and Tikhonov was credited with the goal.

After the 2004–05 lockout, a new rule was instituted that imposes a minor delay-of-game penalty on any defensive player who directs the puck out of bounds (e.g., over the glass into the stands or into the safety netting. When the puck is shot into either of the players’ benches, the penalty will not apply.

There also exist game- and 10-minute-misconducts which are reserved for infractions such as continued disputing of a call with an official or for intent-to-injure penalties. Misconducts do not affect the on-ice strength of the offending team, though they are usually accompanied with a minor, double minor, or five-minute major.

Various combinations of penalties may also result in match-ups such as 5-on-3, 4-on-3, 4-on-4 or (rarely) 3-on-3.

After a penalty is assessed, play resumes with a face-off in the offending team's defensive zone.

Team Roster
Before each game, the coach from each team has to submit a list of players that will take part in the game. The roster can include a maximum of 18 skaters and two goaltenders. 5 skaters and 1 goaltender on the ice, unless there is a penalty call.

Trushinski bylaw
The Trushinski bylaw requires players to have sight in both eyes. Under the bylaw, players who are blind in one or both eyes are ineligible to play in the league.

The rule is named for Frank Trushinski, a minor league hockey player for the Kitchener Greenshirts. Trushinski lost his sight in one eye in a game in 1921, but was allowed to continue playing. In a later game, he suffered a skull fracture which cost him most of the sight in his other eye.

A notable violator of this rule was Willie O'Ree who lost 95% of the sight in his right eye a few years before his NHL debut in 1958.