Network Interface Card(NIC) is used to connect a PC to the the network. It is fixed into one of the computer's expansion slot. In wireless network also NIC is used.It can be identified by a light.
I am pretty sure that a WAN connection would not be needed for a home network. A WAN is a Wide-Area Network. A WAN would be used to connect to your business computer from home. A LAN is a Local-Area...