When a player skates hard toward the goaltender or crease with disregard of his and other's bodies to get to a rebound or attempt to disrupt the goaltender's focus.
The National Hockey League - NHL has taken steps over the years to try and limit players from "crashing the net" too hard, especially when it comes to making contact with the goaltenders in and even outside the crease.
Crashing the net or crease, also referred to as driving hard to the net, does not necessarily mean running over the goalie or knocking the net off all the time. The term can be used to generally describe a player who had worked hard to get in front of the net to create a scoring chance, deflect a shot or screen the goalie.
Players who are best at "Crashing the net" do not take many penalties but often get goaltenders off their game, or score "garbage goals" through their hard work. Tomas Holmstrom and Ryan Smyth are well-known crease crashers. Another player famous for crashing the net was long-time Edmonton Oilers and Hall of Fame NHLer Glenn Anderson.