The offside rule in hockey is meant to keep forwards honest. You cannot just hang out with the opposing goaltender and wait for your team to feed you the puck. In short the first thing that can enter the attacking zone is the puck. But of course, there is more to it than that.
The Offside Rule
Per the NHL Rulebook, the offsides rule is as follows:
83.1 Off-side – Players of the attacking team must not precede the puck into the attacking zone.
This means that a player on the attacking team must have at least one of his skates in contact with or behind the blue line of the offensive zone before the puck completely crosses the line. A stick behind the blue line does nothing. The position of the offensive player’s skates is the determining factor of whether or not he is offside.
Deflections and Rebounds
If a defending player sends the puck out of his zone and it rebounds off one of his defending teammates and back into the zone, offensive players still in the zone are eligible to play the puck without being offside.
If a puck is sent into the offensive zone while an offensive player is in the zone, that player is considered offside. But, if the player does not play the puck or the defending team can clear the puck without coming into contact with the offside player, a delayed offside will occur. Once the offside player clears the offensive zone, the delayed offside will nullify.
Faceoffs Following an Offsides Call
After an offside, the faceoff will take place in the neutral zone on the side of the ice the infraction occurred on. However, if deemed an intentional offside (a violation in which the offending team intentionally goes offsides to stop play) the faceoff will take place in the offending team’s defensive zone.