College basketball games consist of two halves, not periods. Each half lasts 20 minutes of actual playing time, making the total regulation game time 40 minutes. This differs from the NBA, which uses four 12-minute quarters, and high school basketball, which typically uses four 8-minute quarters.
The two-half structure has been standard in college basketball for many decades. The game clock stops during timeouts, fouls, and when the ball goes out of bounds, so the actual elapsed time for a game is typically 2 to 2.5 hours depending on the number of stoppages.
If a game is tied at the end of regulation, overtime periods are played. College basketball uses 5-minute overtime periods, and teams continue playing additional overtimes until one team wins. This can result in multiple overtime periods if the teams remain tied after each 5-minute period.
So while the base regulation game has two halves, not periods, the overtime format does use periods of 5 minutes each. The terminology can sometimes cause confusion, but the two-half structure is the defining characteristic of college basketball's standard game format.