Dictionary.net

A class of methods for sharing a datatransmission medium in which hosts transmit as soon as theyhave data to send and then check to see whether theirtransmission has suffered a collision with another host's.If a collision is detected then the data must be resent. Theresending algorithm should try to minimise the chance that twohosts's data will repeatedly collide. For example, theCSMA/CD protocol used on Ethernet specifies that theyshould then wait for a random time before re-transmitting.See also backoff.This contrasts with slotted protocols and token passing.