Olympic basketball games are played in four 10-minute periods, called quarters.
That gives a regulation game 40 minutes of playing time under international basketball rules. The format is governed by FIBA, whose rules are used in Olympic five-on-five basketball. The clock stops during various dead-ball situations, so an actual game broadcast lasts considerably longer than 40 minutes.
If the score is tied after the fourth quarter, the teams play five-minute overtime periods until one team leads at the end of an overtime. This differs from the NBA, where regulation games use four 12-minute quarters for a total of 48 minutes.
The answer is sometimes confused with Olympic 3x3 basketball. That event uses a single 10-minute game clock, with the first team to 21 points winning immediately. The four-quarter format applies to traditional Olympic five-on-five basketball.