A call made by an on-ice official when a player crosses the blue line into the offensive zone before the puck crosses the blue line. This results in a stoppage in play and the puck being dropped at a faceoff circle just outside the offensive zone blue line.
An offside call will not result if a player on the defending team sends the puck back into their own zone and an attacking player is already in the zone. If an attacking player attempts to pass the puck into the zone and it bounces off a defending player and into the zone after an attacking player is already in the zone, an offside call may still result. The NHL plays by the immediate offside rule. This means the linesman blows the play dead as soon as the violation occurs. Some other leagues play by the delayed offside rule, which allows the defending team to regain control of the puck and move the puck out of their zone. The offside call remains in effect until the puck crosses into the neutral zone. If the defending team does not make an attempt to move the puck forward, the linesman will whistle the play dead and drop the puck at the nearest faceoff dot outside the offensive zone.