The major objective of the book is to provide an introduction to the key concepts of computer communication for metropolitan and wide area networks in a manner that is easily digestible to a new beginner in the field. It provides an overview of the key technologies and describes the technologies with an emphasis on how they work and their key benefits. The book may also serve as a single source of reference to the veteran in the area. It is hope that the book will be beneficial to practising engineers, computer scientists, and information business managers.