The first edition of the book "IO-Link. Intelligent devices need simple interfaces" already gave a basic introduction to the topic. It compared existing solutions and looked upon the continuously changing market demands. This translation of the second, latest and fully revised edition builds seamlessly on the previous edition and its topics. Apart from these pivotal topics, this edition gives a detailed and elaborate outline of the diverse applications of IOLink. The topical introduction provides a primary guidance before technical details and sample applications show the wide spectrum of possibilities of this standard. This book is meant primarily, but not solely for developers and programmers, users and deciders, who want to achieve a valid basic knowledge on IO-Link by way of the profound explanations in this book, but which cannot be found in the specifications as such.