Beginner's Guide to American Football

The NFL operates one of the most comprehensive concussion protocols in professional sports. Any player suspected of sustaining a concussion is immediately removed from the game and evaluated by the team's medical staff in the sideline medical tent or locker room.

Defensive Pass Interference (spot foul + automatic first down): A defender physically hinders a receiver's opportunity to catch a forward pass. Penalty is enforced at the spot of the foul.; Roughing the Passer (15 yards + automatic first down): Hitting the quarterback after the ball has been rele...

The offensive team has four downs (plays) to advance the ball at least 10 yards from the original line of scrimmage. Successfully gaining 10 or more yards results in a new first down.

The NFL and NFLPA jointly test and rank all helmets used in the league via laboratory impact testing. Helmets that do not meet minimum performance thresholds are prohibited.

Replay assist may now review the following safety-related penalties when a flag has been thrown: Facemask fouls; Horse collar tackles; Hitting a defenseless player

Yard lines: Marked every 5 yards across the width of the field, numbered every 10 yards from each goal line to the 50-yard line; Hash marks: Short lines at 1-yard intervals between the yard lines, positioned 70 feet 9 inches from each sideline. All plays begin on or between the hash marks.; Goal ...

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.

An NFL game consists of four 15-minute quarters, divided into two halves with a halftime intermission of approximately 12–15 minutes (longer for special events like the Super Bowl). The game clock ...

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: Positio...

Positioned at the center of the end line (back of the end zone); Crossbar height: 10 feet (3.05 m) above the ground; Uprights: 18 feet 6 inches (5.64 m) apart, extending at least 30 feet above the crossbar