A hardware address, also known as a MAC address (Media Access Control address), is a unique identifier assigned to a network interface controller (NIC). It is a 48-bit number that is typically written in hexadecimal format, with each pair of hexadecimal digits separated by a colon. For example, a hardware address might look like this: 00:11:22:33:44:55.
Hardware addresses are used to identify devices on a network. When a device sends a packet of data, the hardware address of the sender is included in the packet. This allows the recipient of the packet to know which device sent it. Hardware addresses are also used to control access to a network. A network administrator can configure a router or switch to only allow devices with specific hardware addresses to connect to the network.