ARPANET linked four nodesIn 1969, the nacent ARPANET grew to four nodes when ARPA (the U.S. Department of Defense's Advanced Research Projects Agency) connected computer network nodes at four universities: the University of California, Los Angeles (UCLA), the Stanford Research Institute (SRI) in Menlo Park, Calif., U.C. Santa Barbara, and the University of Utah. Initial test login characters had been sent on 29 Oct 1969 from a ULCA computer to a computer at SRI, which were permanently connected on 21 Nov 1969 through early routers (small packet-switching computers then called Interface Message Processors). This “network of networks” eventually evolved into what became known as the Internet of the mid-1980s.«Image: Diagram of ARPA Network, Dec 1969, 4 nodes. From bottom, clockwise, links with computers at UCLA, UCSB, SRI and Utah.