John Graham-Cumming is a wandering programmer who's lived in the UK, California, New York and France. Along the way he's worked for a succession of technology start-ups, written the award-winning open source POPFile email program and churned out articles for publications such as The Guardian newspaper, Dr Dobbs, and Linux Magazine. His first effort writing a book was the obscure and self-published computer manual GNU Make Unleashed which saturated its target market of 100 readers. Because he has a doctorate in computer security he's deeply suspicious of people who insist on being called Dr., but doesn't mind if you refer to him as a geek. He is the proud owner of a three-letter domain name where he hosts his web site: http://www.jgc.org.

Sydney Padua is a cartoonist and visual effects artist. Her cult webcomic The Thrilling Adventures of Lovelace and Babbage, now a bestselling graphic novel, combines extensive research with alternate-universe comic-book escapes, where Babbage's 1840s mechanical computer is finally completed and used to build runaway economic models, defeat spelling errors, and of course, fight crime. Her 3-d animations of how the Analytical Engine would have looked and operated are some of the first visualisations ever created of that extraordinary machine. Her work has been featured in Wired and The Economist and she has spoken at Microsoft, Google, the BBC, and the Computer History Museum.