The Acronym (MAC) Media Access Control or Medium Access Control address (MAC address) is a unique identifier assigned to network interfaces for communications on the physical network segment. MAC addresses are used in the media access control protocol sublayer of the OSI reference model. The MAC layer controls how a computer on the network gains access to the data and permission to transmit it.
A MAC address consists of six bytes or (48 bits), with each byte represented by two hexadecimal digits (0-9 or A-F). The first three bytes (24 bits) identify the manufacturer of the Network Interface Card (NIC) and are known as Organizationally Unique Identifiers (OUIs). The OUIs are registered with IEEE and can be looked up in IEEE’s OUI database.
The last three bytes (24 bits) uniquely identify each NIC manufactured by that organization and are referred to as a device identifier or Extended Unique Identifier (EUI).