The ARPANET (Advanced Research Projects Agency NETwork) was an early computer network, constructed in 1969 as a robust medium to transmit sensitive military data and to connect leading research groups throughout the United States. ARPANET first ran NCP (Network Control Protocol) and subsequently the first version of the Internet protocol or TCP /IP suite, making ARPANET a prominent part of the nascent Internet . ARPANET was closed in early 1990.