A recent trend in distributed systems is to interconnect the distributed elements by means of a multipoint broadcast network. Within industrial communication systems, fieldbus networks are especially intended for the interconnection of process controllers, sensors, and actuators, at the lower levels of the factory automation hierarchy. This book provides a comprehensive study on how to use networks to support industrial communication application. Four parts are roughly included in this book: 1) Fundamentals in communications and networking technologies with their developments. 2) Applications of communications and networking technologies in industry with improvements. 3) Security for communications and networking technologies in industry. 4) Trends for communications and networking technologies in the future. Fundamental theories on communications and networking are introduced in this book. A hierarchy and construction of networks for use in industry and some application instances are also presented. sSome improvement to the application with and networks are also given. Security problems in networking technologies in industry are especially addressed in detail, dealing with related methodologies. Trends for communications and networking technologies in the future areis analyzed and predicted in the last part of this book.