Carrier Sense Multiple Access with Collision Detect (CSMA/CD)
This is a function of Ethernet Networks. Each computer on the network waits for a gap in the traffic before attempting to send data (Carrier Sense). If two computers attempt to send data simultaneously, this is recognised (Collision Detect), both stop and wait two different random times before attempting to send data again, hence avoiding another collision. This system becomes less efficient the more computers are on the network.