This book is an introduction to WeChat applet development for beginners. It consists of 4 parts which are further divided into 12 chapters. Part 1 introduces the origin, first registration and creation of project procedure of applets. Part 2 dissects the framework and components of applets. Part 3 focuses on the application of Web API, media API, file API, data API, location API, device API and interface API in WeChat applets. Part 4 takes an example – design and implementation of a college news applet – to illustrate the integrated application design. This book contains 110 complete application examples, all of them are debugged in WeChat web developer tools and real devices; moreover, there are also a full set of example source codes, exercises and video explanations.