A MAC (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. This use is common in most IEEE 802 networking technologies, including Ethernet, Wi-Fi, and Bluetooth. A MAC address is a 12-digit hexadecimal number (48-bits in length) that is usually represented in human-readable form as six groups of two hexadecimal digits separated by colons or hyphens (e.g. 00:11:22:33:44:55 or 00-11-22-33-44-55). A MAC address is used by the network hardware, such as routers and switches, to identify and forward data to the correct device on a network. MAC addresses are unique to each NIC, and they are burned into the firmware of the device during its manufacturing process, making them permanent and unalterable. This means that no two devices can have the same MAC address on a network. MAC addresses are used in the data link layer (layer 2) of the OSI (Open Systems Interconnection)