In computer networking, a condition that occurs when two or more computers on a network try to transmit signals at the same time. Handling collisions is one of the main functions of a networking access method. For example, in Ethernet networks, collisions often occur when two or more stations attempt to place frames on the wire at the same time. To handle this situation, Ethernet makes use of the access method called Carrier Sense Multiple Access with Collision Detection (CSMA/CD) so that each station takes turns accessing the wire.
When a station begins transmitting a signal and detects a collision, the station stops transmitting and issues a jam signal to tell the other station that a collision has occurred. Both stations then stop transmitting and wait a random interval of time before retransmitting their signals. The amount of time the stations wait before retransmitting increases with the number of collisions occurring on the network.