Carrier Sense Multiple Access/Collision Detection (CSMA/CD)
In order to manage collisions Ethernet uses a protocol called Carrier Sense Multiple Access/Collision Detection (CSMA/CD). CSMA/CD is a type of contention protocol that defines how to respond when a collision is detected, or when two devices attempt to transmit packages simultaneously. Ethernet allows each device to send messages at any time without having to wait for network permission; thus, there is a high possibility that devices may try to send messages at the same time.
After detecting a collision, each device that was transmitting a packet delays a random amount of time before re-transmitting the packet. If another collision occurs, the device waits twice as long before trying to re-transmit.