Hockey moves fast, and some of its rules are called in a split second: a whistle for icing, a penalty that starts a power play, or a third goal that sends hats onto the ice. This section explains those moments for fans who are new to the NHL, with the current NHL rulebook as the source.
Periods, overtime and shootouts
A hockey game has three 20-minute periods, but it takes far longer than 60 minutes. How many periods in hockey explains intermissions, regular-season overtime and the shootout, and why playoff overtime keeps going with full periods until someone scores.
Rules called during play
Icing stops play when a team shoots the puck from its own half past the opposing goal line untouched. The guide covers hybrid icing, the exception for a team killing a penalty, and why the guilty team cannot change lines. The power play begins when a player goes to the penalty box: minor, major and double minor penalties, 5-on-3 situations, delayed penalties and when a power play ends.
Traditions
Three goals by one player in a game is a hat trick. That guide explains why fans throw hats, the natural hat trick, the Gordie Howe hat trick and where the term came from.