(1) A media access method that monitors another station's transmissions. If the data station detects another signal during transmission, it stops transmitting, sends a jam signal, then waits for a variable time before trying again.
(2) A class of medium access procedures that allows multiple stations to access the medium at will, without explicit prior coordination, and avoids contention by way of carrier sense and deference. Contention is resolved by way of collision detection and transmission.