A man who played a key role in the development of the Internet has died. Robert Taylor, who arguably conceived ARPANET, was 85.

Taylor brought together two sets of existing work and ideas at ARPANET, a network at the US Defense Department’s Advanced Research Projects Agency. The idea of a computer network joining together multiple machines had been floating about since at least 1963 but ARPA’s interest in working on it had stalled. Meanwhile two separate sources had independently come up with the idea   of packet switching, meaning data could be broken down, travel over varying routes to increase efficiency and deal with outages and then get reassembled at the destination.

Taylor was the man who not only brought together the ideas but made sure it happened. His office had three separate terminals each remotely accessing a computer from an ARPA-funded project. Thinking back to the talk of a network, Taylor determined that a system was needed so that he could access all three systems from a single terminal. He then oversaw the planning and tendering process that led to ARPANET – based around packet switching – becoming a reality.

The network then expanded, taking in non-military and foreign computers. In the early 1980s it switched to the TCP/IP set of networking protocols, designed to allow multiple networks to communicate with one another, and became part of the wider Internet.

It wasn’t just the Internet that Taylor helped facilitate. In an earlier role at NASA he directed funding to turn Douglas Engelbart’s prototype of a computer mouse into a real product. After leaving ARPA he oversaw Xerox’s development of the Alto, the first personal computer with a graphical user interface and a direct inspiration for the Apple Mac. Taylor went on to run the team that developed AltaVista, one of the first widely used search engines.

In 1999 he received the National Medal of Technology and Innovation with the citation praising his “visionary leadership in the development of modern computing technology, including computer networks, the personal computer and the graphical user interface.”