How is a unique MAC address assigned to a Network Card?

A unique MAC address is assigned to a network card by the device manufacturer during production. The address is a 48-bit identifier, typically represented in hexadecimal format, and is intended to be globally unique. The first half of the MAC address identifies the manufacturer (the Organizationally Unique Identifier or OUI), while the second half is assigned by the manufacturer to ensure that each card has a distinct address. This systematic assignment helps prevent address duplication across devices.