A MAC address (Media Access Control address) is a unique identifier assigned to a network interface controller (NIC) for use as a network address in communications within a network segment. It is a hardware address that is burned into the NIC’s firmware and cannot be changed.
MAC addresses are used to identify devices on a network and to control access to the network. They are also used to track devices as they move from one network segment to another. MAC addresses are typically written in hexadecimal format, with each pair of characters representing one byte of the address.