Head First is a series of introductory instructional books to many topics, published by O'Reilly Media. It stresses an unorthodox, visually intensive, reader-involving combination of puzzles, jokes, nonstandard design and layout, and an engaging, conversational style to immerse the reader in a given topic. Originally, the series covered programming and software engineering, but is now expanding to other topics in science, mathematics and business, due to success. The series was created by Bert Bates and Kathy Sierra, and began with Head First Java in 2003. Source: Wikipedia (en)