What was the name of the internet's progenitor and the first large geographically separated network?

In 1969, work began on Advanced Research Projects Agency Network (ARPANET), the grandfather to the internet. At first, ARPANET was designed to protect the flow of information between military installations. It did this by creating a network of geographically separated computers that could exchange info via NCP. It later became apparent that it was not created for military use only, but for powerful research computers. It was the first operation packet switching network in the world, and the progenitor of the global internet.
Data communications was previously based on the idea of circuit switching, as in the old telephone circuit. However, with packet switching, systems would use communication links to communicate with several machines by assembling packets.

The five major components is processor main memory second memory and input devices and output devices