What is Offside?

A player is offside if he crosses the opponent's blue line before the puck does.

What this tells us

When a player skates ahead of the puck and crosses into the offensive zone before the puck arrives, play stops and a whistle blows. The puck is brought back for a faceoff in the neutral zone. It's designed to prevent players from just camping out in front of the goal waiting for a pass—they have to skate with the puck, not ahead of it.

Limitations

Offside is a binary rule, not a statistic—a play either is or isn't offside. It doesn't appear in analytics the way possession or shooting metrics do, but it shapes how teams move the puck and how forwards position themselves during transition. Understanding offside is essential context for reading any possession metric, since it governs where the puck can legally go.

Example

Your team's forward skates into the offensive zone and is already near the goal line when a teammate behind him passes the puck forward. Whistle—offside. Play restarts with a faceoff back in the neutral zone.