Transmission Control Protocol / Internet Protocol = how computers talk to each other online
There are other protocols that can be used on local networks, like IPX or NetBUI. I don't recall if there is any difference between characters depending the connection in Diablo, though. Practically, with IPX on a home network the game can automatically find another game acting as a host and join. For a TCP/IP connection, the IP address of the computer acting as a server is required, or you need to connect to a server online.
