In Multimaster mode, more than one master may handle the bus at the same time without data corruption by using arbitration.
Arbitration starts as soon as two or more masters place information on the bus at the same time, and stops (arbitration is lost) for the master that intends to send a logical one while the other master sends a logical zero.
As soon as arbitration is lost by a master, it stops sending data and listens to the bus in order to detect a stop. When the stop is detected, the master that has lost arbitration may put its data on the bus by respecting arbitration.
Arbitration is illustrated in Arbitration Cases.