Donald Watts Davies was a British computer scientist at the National Physical Laboratory (NPL) who independently invented packet switching and gave it its name. Inspired by the time-sharing systems he encountered at MIT and at the 1965 IFIP Congress, Davies saw that interactive computing over data links demanded a new kind of communication service: one in which long messages were divided into short, fixed-format units routed independently and reassembled at the destination, so that many bursty conversations could share the same lines efficiently.
In his own account, recorded in a 1988 oral-history interview, Davies first documented the idea in a memo dated November 10, 1965, circulated a more detailed paper that December, and on March 16, 1966 delivered a lecture at NPL to more than a hundred staff. His June 1966 “Proposal for a Digital Communication Network” contained the first use of the word “packet” to distinguish the smaller transmission units from the user’s whole message, along with the concept of an “interface computer” sitting between user equipment and the network. As the Internet Hall of Fame notes, Davies “coined the term ‘packet’,” choosing it after consulting a linguist because it translated cleanly into other languages.
Davies and Paul Baran reached the same essential mechanism independently and from different motives, Baran seeking survivability and Davies seeking efficient interactive data communication. Davies’s terminology and design, however, were the ones adopted by the wider community. When ARPA’s Lawrence Roberts met Davies’s colleague Roger Scantlebury at a 1967 symposium, he took up both the word “packet switching” and the design ideas for the ARPANET.
At NPL, Davies led the construction of the NPL network, one of the first two computer networks in the world to use packet switching; its Mark I became operational around 1969. Though he struggled to secure British funding to scale the experiment into a national network, his laboratory work proved the concept. Davies was inducted into the Internet Hall of Fame, and his coining of “packet” remains embedded in the vocabulary of every network engineer.