The blue line divides a hockey rink into three sections and determines if a player is offside. Defenders often position themselves near the line to protect against turnovers.
Ice hockey requires a rink that is separated into three sections, which are outlined by the blue line. There are two lines in a hockey rink that indicate the transition between each team’s neutral zone and offensive zone. For example, if an offensive player is carrying the puck into the area between the two blue lines, he is in the neutral zone. If he carries the puck across the line towards the opposing team’s goalkeeper, he is said to be in his offensive zone. If he takes that puck back across the opposite line towards his goalkeeper, he has entered his defensive zone.
The blue line is important in determining if a player is offside, meaning the player entered the offensive zone before the puck. If the player has, indeed, crossed before the puck, the referee blows his whistle and the game is dead. Also, if an attacking player enters the offensive zone, leaves it, and then returns while some of his teammates are left there, the referee blows the offside whistle and the game is dead again. If a player crosses the blue line and is offside, play is moved outside the offensive zone to an faceoff spot just inside the neutral zone. Play is now considered neutral, with neither team in control of the puck until the referee drops it face-down.
This line is also important for determining game strategy. Defenders often position themselves near the blue line while their team is in the offensive zone to protect themselves from a turnover. If the other team steals the puck from the offensive team, play shifts to the other side of the ice and defenders are then in a good position to back up and help defend their goal. Because defenders often stay on the line, they are commonly known as “blue facings”.