The hockey rink is divided into three zones: a defensive zone, neutral zone and offensive zone.
The lines that separates the rink into these three zones are the blue lines.
The key purpose of the blue line is to stop players from entering into the offensive zone before the puck has crossed the line. This is to prevent the offence from getting too much of an advantage over the defence in play.
Without the blue line it would be too easy for the forwards to get in behind the defence on the attack.
Therefore, A player is not allowed to enter into the offensive zone before the puck has crossed the blue line. Now the key determination of whether a player has entered into the offensive zone is if the players skates have crossed the blue line before the puck.
It is okay if the players stick or head or body or one skate has gone over the blue line as long as the puck beats both player’s skates over the blue line.
