MAC layer - technical definition

(Media Access Control layer) The protocol that controls access to the physical transmission medium on a LAN. MAC layer functionality is built into the network adapter and includes a unique serial number that identifies each card (see OUI). Common MAC layer standards are the CSMA/CD architecture used in Ethernet and the token passing methods used in Token Ring, FDDI and MAP. The MAC layer is synonymous with the data link layer in the OSI model.