Book excerpt: As an incredibly cheap, credit-card sized computer, the Raspberry Pi is breaking down barriers by encouraging people of all ages to experiment with code and build new systems and objects; and this book provides readers with inspiring and insightful examples to explore and build upon. Written for intermediate to seasoned Raspberry Pi users, this book explores four projects from around the world, explained by their makers. These projects cover five major categories in the digital maker space: music, light, games, home automation, and the Internet of Things.