In the 1960's, people at the Rand Corporation, America's foremost military think tank, were trying to figure out an important strategic problem: how could US authorities talk to each other in the aftermath of a nuclear attack?

RAND is a contraction of "Research AND Development", and was founded as a research agency in Santa Monica, California, after the second world war to help maintain the unique system analysis and operations research skills that had been developed by the US military to manage the unprecedentedly large planning and logistical demands that arose during the global conflict.

The idea was to create a decentralized computer network, whereby every computer was connected to each other. In this case, even if one of the systems was hit, the others would remain unaffected.

Next, each system has to speak the other's 'language' in order for them to communicate. And this was accomplished through a 'protocol' -- a language that is understood by all computer systems.

During the 1980's, Bob Kahn and Vinton Cerf are key members of a team which creates TCP/IP, the common language of all Internet computers. For the first time the loose collection of networks which made up the ARPANET is seen as an "internet", and the Internet as we know it today is born.

Internet Summary -

The Internet we know today was not developed from a single network that simply grew and grew.
In fact it was developed from three different networks, each new network replacing an older one.
The First Internet was the ARPANET.
The ARPANET was later replaced by the NSFNET.
The NSFNET was then replaced by the NAP-based Internet of today.