When is the internet's birthday? There are a series of possible answers as key events happened on different days, with September 2 being considered as one of them.
It was on September 2, 1969 that Leonard Kleinrock and his colleagues gathered in a lab at the University of California, Los Angeles, as two computers passed meaningless test data through a 15-foot grey cable.
Now that doesn't seem similar at all to the internet that we know today, but it was the first node in ARPANET (Advanced Research Projects Agency Network), the computer network that gave birth to the internet.
Although some celebrate the internets birthday today, others say it didn't really have life until October 29 of the same year.
On that day, Kleinrock typed a message and sent it to the second node at Stanford Research Institute. That, Kleinrock has said, was the first breath of life the Internet ever took.
Other key moments in the internet's history:
October 29, 1969: Often regarded as the other key 'birthday' of the internet, this was the day the first message was sent between computers at different sites - when a computer at UCLA sent the message 'login' to a computer at Stanford. Unfortunately, the system crashed, so only 'lo' was sent.
Late 1971: The first emails are sent over the ARPANET network, by Ray Tomlinson - who would also propose the @ sign as being a crucial part of email addresses. Tomlinson says he's forgotten what those first emails actually said, but suspects they were just nonsense text.
1973: The first ARPANET nodes outside of the USA join the network, in the UK and Norway.
January 1985: The first 'top-level domains' - .com, .net, .org, .gov, .edu and .mil - are created.
November 2, 1988: The first major internet worm, written by a student, brings down thousands of computers as it spreads across the network.
Christmas 1990: Tim Berners-Lee, working at nuclear research centre CERN, creates the first World Wide Web server.
August 6, 1991: Berners-Lee announces the World Wide Web to the world, and the web goes public for the first time.
1993: Mosaic, the first graphical web browser, is released, bringing a new level of popularity and accessibility to the web.
4 September, 1998: Larry Page and Sergey Brin incorporate their new search engine company, Google, from a friend's garage in California.