Basketball is considered to be one of the fastest ball sports there is, and there are a number of rules in place to ensure that this remains the case. One such rule is the shot clock, which is used in the NBA and most professional and amateur leagues to ensure that teams do not simply play possession basketball when their team is in the lead, making it impossible for their opponents to get the ball back quickly and without attempting an offensive move.
The Shot Clock is in place from the moment a team gets possession of the ball, and counts down from twenty-four seconds. After that time has elapsed, the team in possession will be penalized if it has not attempted a shot at the basket. The clock is reset the moment a player attempts a shot at the basket or loses possession of the ball. Once the ball is back in the hands of a player on either team, the shot clock resumes counting down from twenty-four seconds.
If a team does keep possession without attempting a shot, the ball is turned over to their opponents at the sideline nearest to the point where the infraction was committed. This ensures that at any given time the team in possession of the ball must be looking to complete an offensive move by attempting a basket before their twenty-four seconds are up. Teams in the lead by a small score with time running out will still endeavor to use all of the shot clock before attempting a shot, but cannot do it for any longer than the specified 24 seconds.