To someone watching an NFL game for the very first time, it may come as a surprise to see coaches, players and staff meeting in the middle of the field to shake hands when the game has not yet finished.
This would never been seen in sports such as soccer, rugby or basketball where both sets of players are expected to give their all until the last second has expired.
However, it is a regular occurrence in the NFL that the winner of a game is decided with time still to play and the losing team can do nothing to change that.
What NFL rules lead to this happeneing?
Firstly, in the NFL each play is started by the team in possession - the offense - and the team on defense can do very little to speed up or slow down the pace of play.
Secondly are the clocks. In an NFL game there are two clocks, the game clock which counts down how much time is left to be played in each quarter and the play clock which counts down how many seconds are left before the offense is forced to snap the ball.
The play clock is usually set at 40 seconds per play but can be reduced to 25 seconds for administrative reasons.
Finally, the NFL has timeouts which teams can use to stop the game clock - three per team per half.
Using a timeout stops the game clock and gives coaches a chance to relay messages to players and give them a chance to catch their breath.
More often than not, timeouts are saved until the latter stages of each half where coaches will use them to manage how much time is left on the game clock.
So how can the game be finished with time left?
The last important piece of information is that teams on offense can make it practically impossible for a defense to steal the ball back while in something called 'victory formation'.
Teams in the NFL do this all the time when their losing opponent has no timeouts left to stop the clock and enough downs left to run out the remainder of the time.
Victory formation consists of the ball being snapped to the quarterback who is standing directly behind the centre, and then the quarterback kneeling down with possession of the ball.
While this often loses a yard, the game clock continues to run and the losing team can do nothing about it.
If a snap takes place in victory formation with under 40 seconds remaining in the game, then the remaining time is when you will see coaches and players meet in the middle of the field to shake hands.
This is because the team in possession has no desire to take another snap, the play clock has more time on it than the game clock and the losing team does not have a timeout remaining.
Instead of both teams waiting on their respective sidelines for 30 seconds, it is custom in the NFL to accept the game is over and shake hands despite their still being time on the game clock.