Distributed coordination function (DCF) is the fundamental medium access control (MAC) technique of the IEEE 802.11-based WLAN standard (including Wi-Fi).
DCF employs a carrier-sense multiple access with collision avoidance (CSMA/CA) with the binary exponential backoff algorithm.
DCF requires a station wishing to transmit to listen for the channel status for a DIFS interval.
In order to avoid such collisions, DCF also specifies random backoff, which forces a station to defer its access to the channel for an extra period.
The IEEE 802.11 standard also defines an optional access method using a point coordination function (PCF).