Officials play a very important role in the game, from keeping the game rolling along and calling penalties when a rule is broken, to making sure the athletes don't unnecessarily hurt each other. Officials are responsible for monitoring the game clock and play clock, enforcing the rules of the game, and recording all rule infractions.
You often hear them referred to by the general term of referee, but there is actually only one referee on the field during a game. Each official (usually seven in college and NFL games) has his own title and assigned responsibilities. Following are the responsibilities of each along with their positioning on the field: