The computer network officially began functioning when it fully substituted previous networking systems January 1, 1983, the Telegraph reported.
On that day, it was the first time the US Department of Defence-commissioned Arpanet network fully switched to use of the Internet protocol suite (IPS) communications system.
This new method of linking computers paved the way for the arrival of the World Wide Web (www).
Based on designs by Welsh scientist Donald Davies, the Arpanet network began as a military project in the late 1960s.
It was developed at many American universities, including the University of California - Los Angeles (UCLA) and the Stanford Research Institute.
In 1973, work on the IPS and Transmission Control Protocol (TCP) technology began. The new systems were designed to replace the more vulnerable Network Control Program (NCP) used previously, and made sure the network was not exposed to a single point of failure.
By January 1 1983, the substitution of the older system for the new Internet protocol had been completed and the Internet was born.
British computer scientist Tim Berners-Lee later used it to host a system of interlinked hypertext documents in 1989, known as the World Wide Web.