Early Days

• In the earliest days of the NFL, only three officials were used to enforce the rules. These were the umpire, linesman and head referee. During these early days, there was only a basic rulebook with which they had to work.
  
  

Additional Officials

• Starting in 1929, the NFL began to add additional officials to assist the core referee team with maintaining proper standards. This included a field judge and a back judge.
  
  

Line Judge

• During the 1960s, a new style of quarterback playing was established in which scrambling was more commonplace. In response to this new type of activity, the line judge was added to the referee team.
  
  

Microphones

• Until 1975, the penalties and rulings were simply stated by the referee team. That year, the NFL decided to add microphones that would allow referees to clarify complex rulings to the game's attendees.
  
  

Side Judge

• The modern system of referees was put into place in 1978 when the NFL added its seventh referee. In an effort to open up the pass game to more efficient rulings, a side judge was added to the lineup.