One of the two sublayers into which the data-link layer (layer 2) of the Open Systems Interconnection (OSI) reference model is subdivided based on the specifications of IEEE Project 802. The other sublayer is the logical link control (LLC) layer. The MAC layer interfaces with the physical layer below it and provides access to and direct communication with the network interface card (NIC).
Essentially, the MAC layer determines which computer on the network is allowed to use the media at any given moment. The MAC layer is thus responsible for implementing the media access control method for the particular network architecture, such as Ethernet or Token Ring. The MAC layer is also responsible for making sure that data is delivered without errors.
The MAC layer receives framed data from the LLC layer immediately above it, which is media independent, and reframes the data, adding a source and destination physical address or MAC address to the frame for transmission on the medium.