Originally, ARPANET linked together defence contractors, universities and research laboratories. But soon, a strange mix of military people, anarchists, academics, science fiction fans, hackers, hippies, and people who just plain loved new technology had all jumped on board. Very quickly, they started using electronic mail. Soon, email became the most useful application (the “killer application” that everybody had to have) of the ARPANET. The ARPANET had very few deep secrets: everything was “open” to see. Military  strategists were used to believing that “important stuff” was secret, and so they thought that something as open as ARPANET was useless to them. So the military kept away. As ARPANET evolved, the computers became faster and more powerful, and the rules that govern how packets moved changed. But around 1982-1983, there was a change back to a single protocol. TCP/IP (otherwise known as Transmission Control Protocol/Internet Protocol) was brought in to control the packets. This was a very important “invention.” Because everybody could now follow the same standard (e.g., for labelling their packets), different small nets could talk to each other. In 1983, the Defence Communications Agency split the network into two parts: ARPANET, basically for the universities and anybody else doing research; and MILNET for non classified military communications. Also in 1983, ARPANET was officially renamed “the Internet.”
