Offside and icing, explained for parents

The offside rule: an attacking player cannot cross the offensive zone's blue line before the puck does. It is the position of the SKATES, not the stick or the body, that determines offside: as long as one skate still touches the blue line or stays behind it, the player is onside, even if their stick reaches into the offensive zone. An offside stops play and brings a faceoff back near the blue line in the neutral zone; the rule exists to stop attackers from camping in front of the opposing blue line waiting for a long pass.

The icing rule: a team cannot fire the puck from its own side of the center red line all the way down the ice, across the opposing goal line, without a teammate touching it first. If an opponent (usually a defenseman) touches the puck first after that long shot, the referee calls icing and brings a faceoff back into the offending team's own defensive zone, a positional penalty that makes the rule a real deterrent.

Both rules chase the same goal: forcing play to build up instead of rewarding the desperate clear or passive waiting. Without offside, the fastest attackers would camp in the opposing zone waiting for long passes; without icing, a team AHEAD on the scoreboard could spend the last minutes firing the puck the length of the ice to run out the clock without ever trying to play. In youth hockey, several associations apply an automatic or hybrid icing variant, which removes the race between skaters to touch the puck first and cuts the risk of a boards collision accordingly.

One useful refinement to know: DELAYED offside. If an attacker is in the offensive zone before the puck but no teammate touches it while the referee is signaling with a raised arm, the player can tag back, skate on or behind the blue line, to become onside again without a whistle. That raised-arm signal, easy to spot from the stands, tells apart delayed offside (still avoidable) from offside already called (too late, back to a faceoff). As long as the arm stays up, no attacker may touch the puck inside the zone: it is that contact, far more than where the skates are at that exact instant, that turns a delayed offside into an actual stoppage, and it is why you sometimes see a whole forward unit back out of the zone instead of chasing the puck down.