Comparison of American football and rugby union
A rugby union game is divided into two halves of 40 minutes (or shorter for lower-grade games, and breaks given halfway through each half if playing conditions are considered to be extreme) separated by a half time period of up to 15 minutes in an international match. Most notably, a rugby union game will continue after the scheduled end of a half (half-time or full-time) until the ball becomes dead - any occurrence that would have play restart with a scrum or lineout, or when a team scores. This has led to some "nail-biting" finishes where teams losing by only a small margin work their way towards scoring, and games can go on several minutes over time. Something similar can occur at the end of either half in American football, though usually for only a few seconds of additional time, because a play that begins before the half expires continues until the ball is dead regardless of whether there is any time left on the clock. In both sports, the clock is also stopped during substitutions and for injuries, so the referee does not need to add stoppage time as is done in soccer/Association football. American football games are made up of four quarters of 15 minutes each (less at the high school and youth levels), but the clock stops and starts according to specific rules, so that a 15-minute quarter lasts much longer.
College basketball
As of the most recent 2017–18 season, NCAA men's games are divided into two halves, each 20 minutes long; NBA games are played in four quarters of 12 minutes each; and WNBA and NCAA women's games are played in 10-minute quarters. The NCAA shot clock gives teams of both sexes 30 seconds to shoot, while the shot clock used in both the NBA and WNBA gives teams 24 seconds. Also, NCAA teams are allowed 10 seconds to move the ball past the halfcourt line (with this rule only having been added to the women's college game in the 2013–14 season), while NBA and WNBA rules allow only 8 seconds. However, like the NBA and WNBA (and high school basketball), during the last minute of each period, the game clock keeps time remaining in the period measured in tenths of a second, rather than full seconds.