Microcontrollers are ubiquitous in the modern world, and their proliferation is expected to continue growing steadily. This book provides in-depth knowledge about their structure, functionality, and programming in a practical manner. Over 200 examples, which are also available for download on the publisher's website, are based on the popular family of AVR 8-bit microcontrollers from Atmel, which are widely used, among other things, through the Arduino project. These controllers are particularly well-suited for introducing the subject due to their clear structure and modern Harvard-RISC architecture. All practical examples have been updated for this newly revised edition to align with the current tools from the manufacturer. The free Atmel Studio is used as the IDE, and the hardware base consists of the X, which is available for about 10 euros.