 On October 29, 1969, the world's first electronic computer network, the ARPANET, was established between nodes at Leonard Kleinrock's lab at UCLA and Douglas Engelbart's lab at the Stanford Research Institute (now SRI International).Another milestone occurred in 1973 when Bob Kahn and Vinton Cerf co-invented Internet Protocol and Transmission Control Protocol while working on ARPANET at the United States Department of Defense.The first TCP/IP-wide area network was operational on January 1, 1983, when the United States' National Science Foundation (NSF) constructed the university network backbone that would later become the NSFNet.