Sept. 2, 2009— -- The Internet is officially over the hill.
Though it might try to hide its graying hairs, it was 40 years ago today that computer scientists at the University of California, Los Angeles, established a network connection between two computers, creating the very first node of what we now know as the Internet.
At the time, Leonard Kleinrock and his colleagues were charged with developing the Advanced Research Projects Agency Network (or ARPANET), a government-funded research project in global computer communications that eventually grew into the Internet.
On Sept. 2, 1969, Kleinrock and his team succeeded in getting two computers to exchange data over a network for the first time.
Although some celebrate the net's birthday today, others say it didn't really have life until October 29 of the same year. On that day, a message was typed by Kleinrock and sent to the second node at Stanford Research Institute. That, Kleinrock has said, "was the first breath of life the Internet ever took."
It's hardly surprising that a system so complex has a hard-to-pin-down date of birth and many say either date suffices.
"It's valid to consider either one because each involved transmission between computers," said Michael A. Banks, a technology writer and author of "On the Way to the Web: The Secret History of the Internet and Its Founders."
Since its academic beginnings, the Internet has come a long way, revolutionizing nearly every aspect of human interaction.
In honor of the occasion, here's a walk down memory lane and a look at some the Internet's most significant milestones.
ARPANET Goes Global, Grows Into the Internet
These services marked a "really big step" in bringing consumers – not just academics and government officials – online, Banks said. Although the users couldn't communicate with users of other networks or access information hosted on other networks, they still formed some of the first vibrant emerging online communities.
"Lives were changed immediately. People stayed online longer and later, fascinated with the ability to interact with several people at once," Banks writes in his book, "On the Way to the Web." "The online world and its denizens took on a new aura of reality, and the online experience grew far more entertaining and unpredictable."
He was sentenced to three years' probation, community service, and a fine of $10,000 plus legal costs. Despite his run-in with the law, he went on to great success, eventually joining a startup that was bought out by Yahoo.
Now, he's a professor in the Computer Science and Artificial Intelligence Laboratory at M.I.T.
Tim Berners-Lee Introduces the 'World Wide Web'
While working at CERN, the European Organization for Nuclear Research, he devised the Web as a way to organize, address and link information on the Internet.
Smart Phones Bring Mobile Internet to Millions
"When it launched it was a Facebook replacement for college. The day it became a genuine platform was when they opened it up," said Harvard's Weinberger.
The Associated Press contributed to this report.