The book 'Digital Communications' is meant for the students of Electronics and Communication, Computer Science, Electrical Engineering, Electrical and Electronics Engineering and Information Technology branches, both at undergraduate and post-graduate levels. In this book, the basic principles involved in the analysis and design of Digital Communication Systems are presented with an overall aim of helping the students to develop an intuitive idea about the theory under discussion. It is a well-designed textbook for self-study as well as a reference for anyone who has interest in studying Digital Communications. The book, though comprehensive, has been developed in a reader-friendly fashion by providing numerous pedagogical aids for the study of Digital Communication Systems.