One of the internet's inventors Leonard Kleinrock remembers the day it began and knows what he'd do differently now.
It's hard to imagine a world without the internet. There'd be no email, no YouTube and certainly no buying online. However just over 40 years ago, that was the case.
It was September 2, 1969 when computer scientists at UCLA created a network connection between two computers. They set up the first node of what has become today's internet.
"This was the day that the infant internet took its first breath of life," said Leonard Kleinrock, a Distinguished Professor of Computer Science at UCLA and one of the men who enabled two computers to exchange data over a network for the very first time.
"It was the first time... this baby came out and looked around and started talking to the world."
As with many things so complicated and historically significant, there's some debate over the actual date of the birth. Some say it was that September day in 69 when the two computers first exchanged data. Others peg it on October 29, 1969, when Kleinrock, who developed the principles behind packet-switching, sent a message to a second node at Stanford Research Institute.
Kleinrock, who received the 2007 National Medal of Science, said both days are significant.
"If September 2 was the day the internet took its first breath, we like to say October 29 was the first day the infant internet said its first words," he said.
While the internet has evolved into something that has woven into daily life, it started out with one test that had the computer scientists involved both exhausted and anxious.
According to Kleinrock, there was a lot of anticipation that day, and about 20 people from the likes of GTE, DARPA, Honeywell and Scientific Data Systems crowded into the computer lab to watch.
"Everybody was ready to point the finger at the other guy if it didn't work. It was beautiful," said Kleinrock.
The router was a brand new Honeywell DDP 516, about the size of an old telephone booth and state of the art at the time, a Scientific Data Systems computer, a 50-foot cable connecting the two - and a lot of faith.
"We were worried that this [Honeywell] machine, which had just been sent across the country, might not operate properly when we first threw the switch," said Kleinrock.
"We were confident the technology was secure. I had simulated the concept of a large data network many, many times. All the connections. Hop-by-hop transmissions. Breaking messages into pieces. The mathematics proved it all and then I simulated it. It was thousands of hours of simulation."
And it did work.
NEXT PAGE: What happened after the initial transmission worked