Final answer:
A MAC address uniquely identifies a network interface for communications at the data link layer of a network. It is a 48-bit number, usually provided by the device manufacturer and embedded within the network interface card.
Step-by-step explanation:
A MAC address, which stands for Media Access Control address, is a unique identifier assigned to network interfaces for communications at the data link layer of a network segment. MAC addresses are used as a network address for most IEEE 802 network technologies, including Ethernet and Wi-Fi.
Within the IEEE 802 standard framework, the MAC address is a unique serial number, and therefore each MAC address is intended to be globally unique. MAC addresses are typically assigned to a device by its manufacturer and are stored in its hardware, such as the network interface card (NIC).
The standard MAC address is a 48-bit (6-byte) number. In hexadecimal format, a MAC address is typically written as six groups of two hexadecimal digits, separated by hyphens (-) or colons (:), like so: 00-1A-2B-3C-4D-5E or 00:1A:2B:3C:4D:5E.
When a device attempts to connect to a network, it broadcasts its MAC address so that the network knows which physical device is trying to join. This is analogous to a person showing their ID to security before entering a secure building, as the MAC address acts as the digital identity of the device.