Quarterbacks kneel to drain the final seconds with minimal turnover risk. Here is how victory formation, the 40-second play clock and timeouts work together.

NFL teams ice kickers to disrupt the field-goal routine, but studies disagree on whether the timeout reliably causes more misses.

An NFL team may intentionally concede two points to burn the final seconds, avoid a dangerous goal-line punt and improve its restart position.

NFL teams decline penalties when the play result creates a better combination of down, distance, field position, possession or clock.

A quarterback spikes the ball to stop a running game clock while saving a timeout—but the offense must sacrifice one down.

An NFL umpire stands over the ball after an offensive substitution so the defense gets a fair chance to match—while the offense's play clock keeps running.

An offensive lineman reports as eligible to change his number status for one play—but alignment still determines whether he may catch a pass.

The NFL emergency third quarterback dresses but stays inactive until both active QBs are unavailable. Learn the 53-man roster rule and entry limits.

The NFL blue medical tent is a private examination space, not an automatic concussion diagnosis. Learn what happens inside and who decides if a player returns.

The NFL clock stops when a runner goes out, but it may restart before the snap. Learn the two late-game cutoffs and the exceptions viewers miss.

NFL hash marks sit only 18 feet 6 inches apart. Learn why they are narrower than college hashes and how the spacing changes plays, defense and kicks.

Eye black is designed to reduce reflected glare near a player’s eyes. Here is what the research says about grease, stickers, contrast and football performance.

Football players wear towels to dry their hands and protect ball control. Learn who uses them, how they differ from hand warmers and the NFL rules.

The official’s hat is a spot marker, not an automatic penalty flag. Learn what it records and when an NFL out-of-bounds ruling changes the play.

NFL helmet radios send one coach's call to one green-dot player before a 15-second cutoff. Learn who can hear it, what happens next and why the rule matters.

A jet sweep gives the ball to a receiver in fast motion. Learn the timing, blocking, rules, touch pass scoring and how defenses stop it.

Quarterbacks identify the Mike to organize protection, not simply to name the middle linebacker. Here is how the count works and why defenses disguise it.

Cover 5, commonly called Two Man, combines man coverage underneath with two deep safeties. Learn every assignment, strength, weakness and offensive answer.

Cushion is the space a corner gives a receiver before the snap. Learn why defenders play off, how leverage changes the technique and what offenses attack.