An official commonly stands over the football to prevent the offense from snapping before the defense has had its allowed opportunity to respond to an offensive substitution. The official moves away when that process…

An NFL player wearing an ordinarily ineligible receiver number must report a change of status to the referee before lining up as an eligible receiver. The referee communicates the number to the defense. That report…

The emergency third quarterback rule lets an NFL team dress a designated inactive quarterback for use if both active quarterbacks become unavailable because of injury or disqualification. It is protection against…

The blue medical tent is a private space for examining an injured NFL player. Its presence tells viewers that an evaluation is happening. It does not identify the injury or establish whether the player will return.

The NFL game clock stops when a runner goes out of bounds, but during much of the game it restarts before the next snap. The referee normally starts it when the ball is ready for play. Specified late half situations…

NFL hash marks keep the next snap relatively close to the middle of the field. The two inbounds lines are 18 feet 6 inches apart, with each line 70 feet 9 inches from its nearest sideline on a field 160 feet wide.

Eye black is a dark coating or strip worn beneath the eyes. Players use it in the hope of reducing nearby reflected glare, and some also wear it as part of a familiar appearance or routine. The evidence supports a…

Football players use towels to remove rain and sweat from their hands between plays. A towel kept at the waist is available before a snap, throw or catch without requiring a trip to the sideline.

An official's hat can mark information the crew may need later in a play. Its most familiar use is recording that a receiver or kicking team player went out of bounds. The hat itself does not automatically mean a…

Bo Nix scored on both preseason possessions after two ankle procedures. What Denver can trust now—and what only the next test can establish.