This new book is designed to provide its readers with sound concepts and knowledge of computers and information technology. Its chapters and their contents are chosen carefully to introduce the readers to important concepts in Computer science, computer applications and information technology through a single book. Each chapter addresses fundamental concepts, popular technologies and current state of the art topics. This book is designed to serve as textbook for various foundation courses in CS, CA, and IT. Students and IT Professionals will find it suitable for use as a reference book as well.