MAC addresses are most often assigned via the manufacturer of a network interface card (NIC) and are saved within its hardware, the card's read-only memory, or a number of else firmware mechanism.
A MAC address usually encodes the manufacturer's registered identification number.
MAC addresses - hardware addresses that uniquely identifies each node of a network.
The standard (IEEE 802) format of MAC-48 addresses in user-friendly form is six groups of two hex digits, separated by colons (:) or hyphens (-), e.g. e8:04:62:90:07:62, 00-1E-37-18-50-DB. Another pattern used by networking equipment (e.g. Cisco) uses three groups of four hexadecimal digits separated by dots (.), e.g. 0016.4d2e.7d10.
Technologies that use the MAC-48 format: 802.11 WiFi networks, Ethernet, Token Ring (IEEE 802.5), Bluetooth, other IEEE 802 networks, FDDI and many others.