Hockey generally has three periods in each game, regardless of what level of hockey is being played.
If a hockey game is tied at the end of the third period, most leagues and rules will call for an overtime period to be played, though individual game circumstances often influence the nature of the overtime period.
In most cases, a shootout is played after (or even instead of) an overtime period.
The three-period model came about prior to the formation of the National Hockey League (NHL). In the early 1900s, hockey followed many other sports by using a two-halves model, but several influential pioneers in the sport believed that a three-period model would create an additional intermission that could be used to keep the ice in better shape for the players.