The two vertical steel bars that are part of the structure of a hockey goal. The goal posts are welded to the crossbar on the top and attached to the cylinder-shaped tube covered with absorption padding that makes up the base of the goal cage on the bottom. A goal is counted anytime the puck ends up in the area between the two goal posts provided it fully crosses the red goal line.
When a puck is shot and directed towards the goal and hits one of the goal posts, it is said that the shot went "off the post". A puck that hits the post may still end up in the net or it may hit the post and deflect elsewhere. When the puck hits the post then ends up in the net, it is said that the shot went "off the post and in"; if it does not end up in the net, the shot went "off the post and out".
It is often said that the goal posts are a goaltender's best friend, because they can sometimes make the save for the goalie. Hall of Fame goaltender Patrick Roy even used to talk to his posts before and during games.