A network interface card is identified on a local area network by a unique 48-bit identifier. This is known as the

The MAC address (Media Access Control) is a 48-bit number (expressed as six 2-digit hexadecimal numbers) that uniquely identifies a device on a local area network. The IP address is used to find the correct network (layer 3), whereas the MAC address is used to find the device on the local area network (layer 2).