A media access control address (MAC address) is a unique identifier assigned to a network interface controller (NIC) for use as a network address in communications within a network segment. This use is common in most IEEE 802 networking technologies including Ethernet Wi-Fi and Bluetooth. Within the Open Systems Interconnection (OSI) network model MAC addresses are used in the medium access control protocol sublayer of the data link layer. As typically represented MAC addresses are recognizable as six groups of two hexadecimal digits separated by hyphens colons or without a separator.

MAC addresses are primarily assigned by device manufacturers and are therefore often referred to as the burned-in address or as an Ethernet hardware address hardware address or physical address. Each address can be stored in hardware such as the card's read-only memory or by a firmware mechanism. Many network interfaces however support changing their MAC address. The address typically includes a manufacturer's organizationally unique identifier (OUI).