Section 4: Players/Officials
Team Composition
Each NFL team carries a 53-man active roster during the regular season, with an additional 17-player practice squad. On game day, teams may activate up to 48 players (46 from the active roster plus 2 practice squad elevations per week). Each team must field exactly 11 players on the field for each play.
Player Positions
Offensive positions include quarterback (QB), running back (RB), fullback (FB), wide receiver (WR), tight end (TE), and five offensive linemen (center, two guards, two tackles). Defensive formations vary but typically include defensive linemen, linebackers, cornerbacks, and safeties. Special teams units include the kicker, punter, long snapper, kick returner, and punt returner.
Substitutions
Free substitution is permitted between plays. Any number of players may enter or leave the field between plays, provided substitutions are completed before the ball is snapped. A team is penalized for having 12 or more players on the field when the ball is snapped (illegal substitution / too many players).
Game Officials (7)
- Referee: The crew chief with final authority on all rule interpretations. Positioned behind the offensive backfield. Wears a white cap (all other officials wear black caps).
- Umpire: Positioned in the defensive backfield. Monitors line play, holding, and illegal use of hands.
- Down Judge: Positioned on the line of scrimmage at the sideline on the chain crew side. Marks the forward progress of the ball.
- Line Judge: Positioned on the line of scrimmage opposite the down judge. Assists with offside, encroachment, and timing.
- Field Judge: Positioned in the defensive backfield on the same side as the line judge. Monitors deep passes and kicks.
- Side Judge: Positioned in the defensive backfield on the same side as the down judge.
- Back Judge: Positioned deep in the defensive backfield. Monitors the play clock and deep pass plays.
First Down Measurement
The NFL now uses Sony Hawk-Eye technology (virtual first-down measurement) as the primary measurement system at all 30 stadiums. Traditional chain crews remain as a backup. The system provides precise, camera-based determination of whether a first down has been achieved.