The part of the ice that houses the goal of your team, and extends out to the blue line. Between the two blue lines lies the neutral zone, and the other end is known as the offensive zone.
The defensive zone is a critical part of the ice for most good teams. Many teams practice players' positioning and how they will react when the other team's offense begins applying pressure.
Besides playing defense and blocking shots or checking the other team, it's also important for teams, once they gain possesion of the puck, to be able to make quick passes and plays to get the puck out of the defensive zone. Teams will spend portions of their practices working on playing defense and then transitioning the puck quickly to the forwards so they can go on the attack - also known as "breakouts."
Although defenseman and centres will play down low and wingers will guard the points in the defensive zone, the players will interchange and flow freely to react to the other team's offense.
The defensive zone also marks where players are penalized for delay of game if they shoot the puck out over the glass without it deflecting off the other team or glass. The rule was instituted in 2005.