Leonard Kleinrock was the first to publish a paper about the idea of packet switching, which is essential to the Internet. He did so in 1961. Packet switching is the idea that packets of data can be "routed" from one place to another based on address information carried in the data, much like the address on a letter. Packet switching replaces the older concept of "circuit switching," in which an actual electrical circuit is established all the way from the source to the destination. Circuit switching was the idea behind traditional telephone exchanges.
The big advantage of packet switching: a physical connection can carry packets for many different purposes at the same time, depending on how heavy the traffic is. This is much more efficient than tying up a physical connection for the entire duration of a phone call. And for services like the World Wide Web, where traffic comes in bursts, it's essential.
What if Google needed a separate modem and phone line to talk to every user, like an old-fashioned BBS (Bulletin Board System)? Handling millions of users would be prohibitively expensive.
With packet switching, packets destined for thousands or millions of users can share a single physical connection to the Internet.
Larry G. Roberts created the first functioning long-distance computer networks in 1965 and designed the Advanced Research Projects Agency Network (ARPANET), the seed from which the modern Internet grew, in 1966.
Bob Kahn and Vint Cerf invented the Transmission Control Protocol (TCP) which moves data on the modern Internet, in 1972 and 1973. If any two people "invented the Internet," it was Kahn and Cerf - but they have publicly stated that "no one person or group of people" invented the Internet.
Radia Perlman invented the spanning tree algorithm in the 1980s. Her spanning tree algorithm allows efficient bridging between separate networks. Without a good bridging solution, large-scale networks like the Internet would be impractical.
The Internet was well-established before Tim Berners-Lee and Robert Cailliau created what is now its most popular application. A major achievement? Of course! But we don't ask why Karl Benz doesn't get some of the credit for inventing the wheel. We understand that the wheel was around before the car.
For more information, see my articles what is the difference between the Internet and the World Wide Web? and who invented the World Wide Web?
"What about Al Gore? Did Al Gore invent the Internet?"
No, former United States Vice President Al Gore did not invent the Internet. What's more, he never said he did!
Al Gore's political contributions to the development of the Internet as we know it were quite significant. For more about this issue, including what Gore really said and how some of the Internet's actual inventors feel about his remarks, see my article Did Al Gore invent the Internet?
"What about Philip Emeagwali? Wasn't he a father of the Internet?"
No. Emeagwali did supercomputing research in the eighties. But his work did not relate to the Internet in any meaningful way. He contributed to no Internet standards, major or minor. Unfortunately he has made public claims that suggest he contributed to the development of something he had nothing to do with. For more information and complete references, see my article Is Philip Emeagwali a "Father of the Internet?"
By 1983, TCP was the standard and ARPANET began to resemble the modern Internet in many respects. The ARPANET itself was taken out of commission in 1990. Most restrictions on commercial Internet traffic ended in 1991, with the last limitations removed in 1995. For a much more complete history of the Internet, see the website of the Internet Society.
Note that the Internet and the World Wide Web are not the same thing. See also: who invented the World Wide Web?, What is the difference between the World Wide Web and the Internet?
See also Hobbes' Internet Timeline for another excellent history of the Internet which includes later important events.
Got a LiveJournal account? Keep up with the latest articles in this FAQ by adding our syndicated feed to your friends list!