One of the interesting things about hockey is that all the players have to be aware of and involved in what is going on all over the rink. Every movement of the puck and the opposing team's players demands a reaction from each player on the team. Forwards must be responsible for defending their own zone, and defensemen must play a role in the offense. Forwards tend to stick to one position for most of their careers, but they move around a bit from time to time as the team needs them to or if the coach thinks, for example, that a left wing might be better suited to playing at center. Defensemen are more flexible, in that they can usually play either side, and some will occasionally fill in at a forward position.
Goalies are very specialized players.
They have to stand in front of the net and stop pucks, some of which are travelling at 90 miles per hour or more. The equipment Each player carries a stick and the players use these sticks to pass and shoot a puck, a small, hard rubber disk, around the rink. In order to avoid being hurt by the sticks and the pucks, the players wear a good deal of padding and they are required by league rules to wear helmets. This is a relatively new rule in the NHL, and many players were resistant to the wearing of helmets when it was first instituted. There is still a certain amount of macho resistance to wearing face shields, probably because it is bad form to fight when wearing a face shield and, therefor, wearing one proclaims a player to be something of a sissy.