What does "physical address extension" mean on system properties info window?

Question

New computer.....

Answer 1

Generally the Physical Address is the eithernet cards MAC address looks something like 00:01:02:03:04:05 This is actually the network cards manufacturers id for that specific network adapter. (Most users will never have to worry about it or use it for anything)

It is used to ID your computer on a network and assure it is seperate from other computers on the same network.