Few were paying attention back on Sept. 2, 1969, when about 20 people gathered in Kleinrock's lab at the University of California, Los Angeles, to watch as two bulky computers passed meaningless test data through a 15-foot gray cable.
That was the beginning of the fledgling Arpanet network. Stanford Research Institute joined a month later, and UC Santa Barbara and the University of Utah did by year's end.
The 1970s brought e-mail and the TCP/IP communications protocols, which allowed multiple networks to connect - and formed the Internet. The '80s gave birth to an addressing system with suffixes like ".com" and ".org" in widespread use today.
The Internet didn't become a household word until the '90s, though, after a British physicist, Tim Berners-Lee, invented the Web, a subset of the Internet that makes it easier to link resources across disparate locations. Meanwhile, service providers like America Online connected millions of people for the first time.
That early obscurity helped the Internet blossom, free from regulatory and commercial constraints that might discourage or even prohibit experimentation.