The number of players on a hockey team depends on the level of play involved. In the NHL, the maximum number of players allowed on the roster is 23. In NCAA hockey, teams can only carry 18 scholarship players. Olympic rosters have the highest number of players at 25.
Only six players per side are allowed on the ice at any given time. This normally translates to three offensive forwards, two defensemen and a goalkeeper. The typical hockey roster has a mix of the first two positions but usually only two goalkeepers. On rare occasions, a goalkeeper may be substituted for an extra attacker.
All the players have specific jobs. A team scores by placing the puck in their opponent's goal, but the goalie's responsibility is to keep the puck out of this net. The defenders support the goalie by interrupting their opponents' play when it comes near the goal. The center and wings are primarily responsible for trying to score. However, when the other team has control of the puck, these players try to regain control of it.