David Griffiths began programming at age 12, after being inspired by a documentary on the work of Seymour Papert. At age 15 he wrote an implementation of Papert's computer language LOGO. After studying Pure Mathematics at University, he began writing code for computers and magazine articles for humans and he is currently an agile coach with Exoftware in the UK, helping people to create simpler, more valuable software. He spends his free time traveling and time with his lovely wife, Dawn. Dawn Griffiths started life as a mathematician at a top UK university. She was awarded a First-Class Honours degree in Mathematics, and was offered a university scholarship to undertake a PhD studying particularly rare breeds of differential equations. She moved away from academia when she realized that people would stop talking to her at parties, and went on to pursue a career in software development instead. She currently combines IT consultancy with writing and mathematics. When Dawn's not working on Head First books, you'll find her honing her Tai Chi skills, making bobbin lace or cooking nice meals. She hasn't yet mastered the art of doing all three at the same time. She also enjoys traveling, and spending time with her lovely husband, David.