American football
Football games last for a total of 60 minutes in professional and college play and are divided into two-halves of 30 minutes and four-quarters of 15 minutes. High school football games are 48 minutes in length with two-halves of 24 minutes and four-quarters of 12 minutes. The two-halves are separated by a halftime period, and the first and third quarters are also followed by a short break. Prior to the start of the game, the referee and team captains for each team meet at midfield for a coin toss. The visiting team is allowed to call 'heads' or 'tails'; the winner of the toss is allowed to decide between choosing whether to receive or kick off the ball or choosing which goal they want to defend, but they can also defer their choice until the second half. The losing team, unless the winning team decides to defer, is allowed to choose the option the winning team did not select, and receives the option to receive, kick, or select a goal to defend to begin the second half. Most teams choose to receive or defer, because choosing to kick the ball to start the game would allow the other team to choose which goal to defend. Teams switch goals following the first and third quarters. If a down is in progress when a quarter ends, play continues until the down is completed.
One-minute warning
At the one-minute mark of any given half or overtime, the referee announces: "One Minute Timing Rule in effect". During the final minute of play, the game clock changes from a continuously running clock (except for scores and time-outs) to a clock that mirrors NCAA rules (stopping on first downs, out of bounds, incompletions, and so on.) Since 2018 teams can do "sandbagging" via the quarterback kneel, a tactic common in the NCAA and NFL to run out the clock with minimum risk. It also rewards defensive play, as a tackle for loss automatically stops the clock. Any player injured during this time and that team uses a timeout.
In the former X-League, after the one-minute warning or in overtime, the "X-Bonus" rule came into play. All scoring during the final minute of play was worth double what it is normally worth, and a special black football was used.