Roller inline hockey, or inline hockey is a variant of hockey played on a hard, smooth surface, with players using inline skates to move and hockey sticks to shoot a hard, plastic puck into their opponent's goal to score points. The sport is a very fast-paced and free-flowing game and is considered a contact sport, but body checking is prohibited. There are five players including the goalkeeper from each team on the rink at a time, while teams normally consist of 16 players. There are professional leagues, one of which is the National Roller Hockey League (NRHL). While it is not a contact sport, there are exceptions, i.e. the NRHL involves fighting. Unlike ice hockey, there are no blue lines or defensive zones in roller hockey. This means that, according to most rule codes, there are no offsides or icings that can occur during game play. This along with fewer players on the rink allows for faster gameplay. There are traditionally two 20-minute periods or four 10-minute periods with a stopped clock. (Source: Wikipedia.org, CC BY-SA)