(1) Contention means competition for resources. The term is used especially in networks to describe the situation where two or more nodes attempt to transmit a message across the same wire at the same time.
(2) A type of network protocol that allows nodes to contend for network access. That is, two or more nodes may try to send messages across the network simultaneously. The contention protocol defines what happens when this occurs. The most widely used contention protocol is CSMA/CD, used by Ethernet. Also see polling and token passing.