On that date, engineers at the University of California at Los Angeles (UCLA) sent a message to their counterparts at the Stanford Research Institute (SRI) in San Francisco, a distance of about 400 miles. In a modern-era equivalent of the legendary first telephone message -- "Watson, come here" -- an engineer named Charley Kline at UCLA tried to log in remotely.

"L," "O," ...

According to news reports, he first typed in the letter "L" and then, by phone, asked an engineer at SRI if the letter had arrived. When that was confirmed, it was on to completing the word "log." The arrival of the "O" was also verified by phone, but the system crashed on "G."

The problem was debugged, and now, four decades later, the world has changed.

Brad Shimmin, an analyst with industry research firm Current Analysis, said he likens the birth of the Internet to the invention of roads. "Roads," he pointed out, "were a key reason for the dominance of the Roman Empire" and the U.S. has been profoundly shaped by its interstate highway system.

The Internet or something like it was as inevitable as roads, Shimmin said. "The desire to communicate" is primal, he noted, and communicating through computing devices grows out of that. It might have grown up in ways other than the IP-based, cobbled-together system of the Internet, he said, but it would have happened.

That original research project, funded by the U.S. Department of Defense's Advanced Research Projects Agency, was propelled by duplicate funding requests from various academic and research institutions. ARPA wanted the institutions to share their research.

At First, Negative Reactions

M.I.T.'s Dr. Larry Roberts, who created the basic technical specs of what was then called ARPANET, recalled recently that initial reactions to the early Internet were quite negative. Institutions, he told the BBC, wanted to keep control of their bulky computers, but soon found out that they could get more computing power at lower overall cost if they worked together.

The ARPANET engineers, he said, knew the project "would change the face of research and development and business."

Before ARPANET, computers could be networked in dedicated sessions, but the costs and time to do so made it impractical and inefficient. By using packet switching, which the 1969 launch demonstrated, costs and ease of connection could be dramatically improved. Packet switching allows data to be broken up into smaller chunks for transmission using a network of computers, and then reassembled at the destination.

Even though Oct. 29 is the generally accepted birthday for the Internet, that is subject to some dispute. While it was the date a message was sent from a lab in one city to a lab in another, some people consider Sept. 2 as the birthday. On Sept. 2, 1969, a message was also sent from one computer to another -- a distance of 15 feet inside the UCLA lab.