What is hockey blue line?

Answer 1

The blue line is used for offsides calls. When a player has the puck and is going towards the oppossing goal his team can't past the blue line till he crosses it with the puck. Also if the the whole team is inside the blue line on the opposing teams side and the puck goes back over the blue line to center ice the team has to go back over the blue line towards center Ice till one of their teammates crosses the blue line again with the puck so the rest of the team can cross it with him. The reason for the rule is so no one can wait by the opposing teams goal for a pass all the way down the ice while all the action could be in the middle of the rink or on their goal