The center red line is the most notable red line on the ice. The center red line cuts through the middle of the ice and divides the ice into two halves. In addition to diving the ice into two halves, the main purpose of the center red line is to enforce the icing rule. The icing rule states that the player in possession of the puck must cross the center red line before hitting the puck into the offensive zone. There are a few exceptions to the icing rule. If the team who dumps the puck is shorthanded, they do not have to be ahead of the center red line. Another exception is, if the puck is dumped on goal or the goalie is the first player to play the puck.
The red goal lines in each team's defensive zone serve two important functions. First, like the center red line, it helps to enforce the icing penalty. In order for a play to be counted as icing, the puck must go past the red goal line. Secondly, the red goal lines also help determine what is a goal. There are two nets on each end of a hockey rink. In order for a play to be considered a goal, the puck must go into the net and completely pass the red line. If the puck does not go completely across the red line then it will not be considered by a goal. There have been a lot of very close calls in the history of the NHL and referees will often use instant replay to get a better look and determine if the puck has fully crossed the line.
There are three main red lines in hockey, the center red line and the two red goal lines in each team's defensive zones. The center red line is 12 inches thick while the two red goal lines are much smaller, spanning 2 inches wide. Both lines aid in the enforcement of the icing rule and the goal lines also aid in determining what is a goal and what is not.
"Dumping the puck" in hockey is a popular tactic where the player in possession of the puck shoots the puck down the ice away from the goal. There are a few reasons and advantages to dumping the puck. First, dumping the puck forces the opposing team to go back and fetch it which allows the team in possession to make substitutions or change lines. Another strategy is to chase after the puck and put pressure on the defense, forcing them into a turnover in their own defensive zone.
In 2005, the NHL removed the red line. They did not remove the physical red line, but the metaphorical removal of the red line got rid of the 2-line pass rule. The 2-line pass rule stated that a player could not make a pass that spanned 2 lines. This meant that a player could not make a pass from their defensive zone over the center red line. The removal of this rule has improved the speed of the game.
In the NHL, goaltenders are not allowed to play the puck over the center red line. In fact, goaltenders are not allowed to interfere with the play by any means across the red line. If they do this, they will be whistled for a minor penalty and there will be a stoppage in play. If a team is trailing with a few minutes left and needs to push for a goal, they will pull their goalie and bring on a skater who is free to roam wherever they want on the ice.