What is a power play?

Answer 1

A Power Play occurs after a penalty. Normally, after a penalty, a player goes to the penalty box to serve time for an infraction. That leaves his team shorthanded. So instead of it being 5 on 5, it is 5 on 4, thus giving the full team a power play.

In addition, during a power play, the team with the man advantage will put out a "power play unit" to get the team's best shooters and passers out there to try to score while the other team is short by a man.

The team that is a man short will try to defend by forming a 4 man box, with 2 players by their net, to help the goalie, and two others out at the blue line trying to block shots and cut off passes. The team that is short one man will try to change their "penalty killers" as fast as possible to keep fresh men on the ice. They do this by shooting the puck down the ice at every opportunity to "use up the clock". This forces the attacking team to go back and get the puck and then bring it back up the ice, wasting time as they do so.

That is correct, though i might add that penalty killers are now being used differently than in the past, as they are now much more aggressive, as they try to score even as they are short a player. This is called a "shorhanded goal". They do "use up the clock" as well. When the team that has the man advantage scores, it is called a "powerplay goal".