On November 22, 1977, as it motored down the street somewhere south of San Francisco, a souped-up delivery van sent some information to a computer lab at the University of Southern California, 400 miles away. No one can quite remember what the information was, but that really doesn't matter. What matters is the way it traveled.
It didn't travel as the crow flies. It traveled from San Francisco to Boston, before a trip to Norway and Britain. And from Britain, it bounced back to Southern California by way of a tiny town in West Virginia.
And it didn't travel over one data network. Thanks to a certain protocol called TCP, it traveled over three: a wireless packet radio network covering a few California hilltops, a satellite hookup bridging the Atlantic, and the Arpanet, a wired network that would go on to much bigger things.
Jon Postel's RFC 793, written in September 1981, is one of the most readable RFCs I have seen.