What does a MAC address uniquely identify?

A MAC address uniquely identifies an individual network interface card. This address is a hardware identifier for a specific network interface, such as Ethernet or Wi-Fi, that is embedded in the device by the manufacturer. Each MAC address is designed to be unique, ensuring that each network interface can be distinctly recognized on a local network.

In a typical networking environment, the MAC address operates at the data link layer of the OSI model, facilitating communication between devices on the same local network segment. When packets are transmitted over the local area network, they include the MAC address of both the sender and the receiver, which allows switches to intelligently forward data to the correct destination device.

This unique identification is critical for network management, allowing devices to connect and communicate without addressing conflicts. The MAC address does not change like an IP address might, which can vary based on the network a device is connected to. Instead, the MAC address stays consistent for the physical network card over its lifetime, making it a reliable identifier for managing network traffic.