John Christopher Wells (born 11 March 1939) is a British phonetician and Esperantist. Wells is a professor emeritus at University College London, where until his retirement in 2006 he held the departmental chair in phonetics. He is known for his work on the Esperanto language and his invention of the standard lexical sets and the X-SAMPA phonetic script system. Career Wells earned his bachelor's degree at Trinity College, Cambridge and his master's degree and his PhD at the University of London. Wells is known for his book and cassette Accents of English, the book and CD The Sounds of the IPA, Lingvistikaj Aspektoj de Esperanto, and the Longman Pronunciation Dictionary. He is the author of the most widely used English-Esperanto dictionary. Until his retirement, Wells directed a two-week summer course in phonetics for University College London, focusing on practical and theoretical phonetics, as well as aspects of teaching phonetics. The course ends with written and oral examinations, for which the IPA Certificate of Proficiency in the Phonetics of English is awarded. From 2003 to 2007 he was president of the International Phonetic Association. He is also a member of the six-man Academic Advisory Committee at Linguaphone. Wells has long been a pioneer of new technology. He is the inventor of the X-SAMPA ASCII phonetic alphabet for use in digital computers that could not handle IPA symbols. He learned HTML during the mid-1990s, and he created a Web page that compiled media references to Estuary English, although he was sceptical of the concept. After retirement, Wells ran a regular blog on phonetic topics from March 2006 to April 2013. He announced the end of his blog on 22 April 2013 saying, "if I have nothing new to say, then the best plan is to stop talking." Work on accents of English A considerable part of Wells's research focuses on the phonetic description of varieties of English. In 1982, Cambridge University Press published his three volumes of Accents of English that described accents all over the English-speaking world in phonetic terminology. This applied consistent terminology to accents that had previously been analysed in isolation. Accents of English defined the concept of lexical sets, a concept in wide usage. A lexical set is a set of words (named with a designated element) that share a special characteristic. For example, words belonging to lexical set BATH have the phoneme in the United States and