ARPAnet 
Advanced Research Projects Agency Network 
In the late 1960s, when the U.S. military feared a nuclear attack from the Soviet Union, government computer scientists in the Advanced Research Projects Agency got together to design a bombproof network that would connect military bases and other military agencies. The system they created linked distant computers via a newly developed set of protocols called TCP/IP. This new network became ARPAnet. In the early 1980s, ARPAnet technology was put to use for civilian purposes and gradually grew into what we now call the Internet. ARPAnet was taken out of commission in favor of a higher-speed network called NSFNET in 1990.