App Inventor is a simple application development environment (ADE) for android applications, created by Google and currently the property of the Massachusetts Institute of Technology (MIT). It was intended above all for teaching beginner programmers who wanted to create and develop simple applications. The straightforward and intuitive interface was designed with this in mind, using blocks of colour and different shapes that fit together like a jigsaw puzzle. Young readers will find this guide easy and simple, with step-by-step instructions for creating their own projects: games, quizzes and animations. They can also personalize their projects using all the potential of this incredible open source tool.