Below is the list of positions for rugby union, there are 15 players a side, generally divided into 8 forwards, and 7 backs. The forwards are the players in the scrums. They are likened to the linemen in American Football, except in rugby any one can run the ball. The backs are usually the faster, more agile players. They are like the running backs of American football. The scrumhalf is the link between the forwards and the backs. There are no substitutions unlike football. This means that the players must play offense and defense.