|  | 6.3 | MAC Addressing
| 6.3.3 | How the NIC uses MAC addresses

Ethernet and 802.3 LANs are broadcast networks. All stations see all frames. Each station must examine every frame to determine whether that station is a destination. On an Ethernet network, when one device wants to send data to another device, it can open a communication pathway to the other device by using its MAC address. When a source device sends data out on a network, the data carries the MAC address of its intended destination. As this data propagates along the network media, the NIC in each device on the network checks to see if its MAC address matches the physical destination address carried by the data frame. If there is no match, the NIC discards the data frame.

As data travels along the wire, the NIC in each station checks it. The NIC verifies the destination address in the frame header to determine if the packet is properly addressed. When the data passes its destination station, the NIC for that station makes a copy, takes the data out of the envelope and gives it to the computer.