Ice hockey is played on a large flat area of ice, using a three-inch-diameter (76.2 mm) vulcanized rubber disc called a puck. This puck is often frozen before high-level games to decrease the amount of bouncing and friction on the ice. The game is contested between two teams of skaters. The game is played all over North America, Europe and in many other countries around the world to varying extent. It is the most popular sport in Canada, Finland, Latvia, the Czech Republic, and Slovakia.