From a Wall Street Journal story by Emily Bobrow headlined “Vint Cerf Helped Create the Internet on the Back of an Envelope”:

Much has changed in the world of cyberspace since Jan. 1, 1983, the date often called “the birthday of the internet.” Yet the internet’s fundamental architecture—the communications protocol that allows computer networks all over the world to talk to each other—remains essentially the same. This is largely thanks to a design that Vint Cerf sketched on the back of an envelope while holed up with fellow computer scientist Robert Kahn in a Palo Alto cabana nearly 50 years ago.