Editing Network topology (section)

===Network interfaces===
[[File:ForeRunnerLE 25 ATM Network Interface (1).jpg|thumb|right|alt=A network interface circuit with port for ATM|An [[Asynchronous Transfer Mode|ATM]] network interface in the form of an accessory card. A lot of network interfaces are built-in.]]
A [[network interface controller]] (NIC) is [[computer hardware]] that provides a computer with the ability to access the transmission media, and has the ability to process low-level network information. For example, the NIC may have a connector for accepting a cable, or an aerial for wireless transmission and reception, and the associated circuitry.

The NIC responds to traffic addressed to a [[network address]] for either the NIC or the computer as a whole.

In [[Ethernet]] networks, each network interface controller has a unique [[MAC address|Media Access Control]] (MAC) address—usually stored in the controller's permanent memory. To avoid address conflicts between network devices, the [[Institute of Electrical and Electronics Engineers]] (IEEE) maintains and administers MAC address uniqueness. The size of an Ethernet MAC address is six [[Octet (computing)|octets]]. The three most significant octets are reserved to identify NIC manufacturers. These manufacturers, using only their assigned prefixes, uniquely assign the three least-significant octets of every Ethernet interface they produce.