Information systems are virtual systems that enable the organization, storage and creation of information which can be accessed and manipulated in an easy and effortless manner. This book on information systems discusses topics related to the processes and protocols involved in information storage and retrieval. Communication is the major field in which information systems are involved as these require rapid processing of large quantities of data as well as its storage, retrieval and manipulation. This book traces the progress of this field and highlights some of its key concepts and applications. A number of latest researches have been included to keep the readers up-to-date with the global concepts in this area of study. It aims to serve as a resource guide for students and experts alike and contribute to the growth of the discipline.