PROFINET are industrial Ethernet networks connecting sensors, actuators and real-time controllers to operator panels, product planning and ordering systems. The technology represented a huge advance over the systems of the 2000s when many fieldbus systems were maturing and industrial Ethernet appearing in automation systems. PROFINET builds on the advantages of the fieldbus systems, especially PROFIBUS. For example, PROFINET enables simple automation system integration with the Internet and is merging with the new development in IoT (Internet of Things), becoming the backbone of the 4th industrial revolution (Industry 4.0). This book is based on the success of the series, PROFIBUS in Practice, answering the need for guidelines on optimising design of PROFINET networks, for good engineering practice in installation, troubleshooting and maintenance. The aim is to bring about improved and standardised engineering practice in applications of PROFINET through sharing a greater understanding of the technology basics, the components, the engineering tools and exploring examples of PROFINET systems. The book covers the PROFINET theory and engineering practice; contains a large number of images and over 200 figures to help better understanding PROFINET techniques. The book provides comprehensive preparatory reading for the internationally recognised Certified PROFINET Installer and Engineer course and the MSc Industrial Communication Systems course which I have been teaching at the Manchester Metropolitan University for a number of years. My tutorial questions are included to support self-learning and preparation for examination.PROFINET is new and the book is a timely effort to provide a practical resource to technology decision-makers, application engineers, production/operation continuity strategy managers and students of mechanical, electrical and electronic engineering disciplines.