I have posted an excerpt from a NerdTV interview of networking pioneer and TCP/IP co-inventor Bob Kahn. At the start of the excerpt he is talking about the ARPANet. The ARPANet was a single network, like a large LAN. The next step was to inter-connect multiple networks, to create an inter-network. Kahn and his colleague Vint Cerf invented TCP/IP to do that. The initial goal of TCP (later split into TCP and IP) was to connect the ARPANet with two other networks each of which had different packet sizes, data rates and communication protocols. TCP/IP has ended up connecting millions of dissimilar networks (3 minutes 33 seconds).