Pratchett's first published work was the short story The Hades Business, published in his school magazine when he was 13, and subsequently reprinted in Science Fantasy magazine in 1961, for which he was paid £14. His second published work was Night Dweller which appeared in New Worlds[?] magazine, issue 156 in November 1965.
Originally employed on leaving school in 1965 as a local newspaper journalist on the Bucks Free Press ("I started work one morning and saw my first body two hours later, 'on-the-job training' meaning something in those days"), he became Press Officer for the Central Electricity Generating Board in an area which covered several nuclear power stations, just following the Three Mile Island nuclear accident in the USA.
It was during his time as a journalist that he was sent to interview Peter Bander van Duren, a co-director of a small publishing company in Gerrards Cross, Buckinghamshire, Colin Smythe Limited, about a new book the company was publishing and Pratchett happened to mention that he'd written a novel of his own, The Carpet People. The rest is history...
He gave up his work for the CEGB in 1987 when he realised he was earning several times as much money from his occasional writing; this allowed him to increase his output and he now typically writes two Discworld books in most years. It has been estimated that 1% of all fiction books sold in Britain are written by Pratchett.
Now containing some 27 books, the Discworld series is a humorous fantasy work that parodies everything under the sun where the disc-shaped world rotates on the backs of four giant elephants supported by the enormous turtle Great A'Tuin swimming its way through space. Major topics of parody have included many science fiction and fantasy characters, ideas and tropes, Ingmar Bergman films, Australia, film making, newspaper publishing, rock and roll music, religion, philosophy (mainly Greek), Egyptian history, trade unions, monarchy, and on and on.
The Colour of Magic[?], The Light Fantastic[?], Mort, and Guards! Guards![?] have all been adapted as graphic novels. Several have also been adapted as plays by Stephen Briggs[?]. Mort and Soul Music[?] have also been adapted as animated cartoons.
Pratchett's books have received a level of critical acclaim unusual for their genre. A collection of essays about his writings is compiled in the book, Terry Pratchett: Guilty of Literature?, eds. Andrew M. Butler[?], Edward James[?] and Farah Mendlesohn[?], Science Fiction Foundation, 2000.
First editions of the early Discworld books in good condition are very valuable - the British first hardcover edition of The Colour of Magic is now worth over £2000 (4,500 copies were printed by St Martin's Press in the USA, of which 506 were sold in Britain under the Colin Smythe imprint, hence the scarcity!), while The Light Fantastic is worth £1000-1500.
It is even possible to get a character in one of the future Discworld books named after yourself. Usually people appear in the books by bidding for the privilege in charity auctions.
Pratchett was one of the first authors to use the Internet to communicate with fans, and has been a contributor to the Usenet newsgroup alt.fan.pratchett for over a decade.