The book 'Digital Principles And Logic Design Techniques' is intended as a textbook for BE/B.Tech degree courses in Electronics and Communication Engineering, Electrical and Electronics Engineering, Electronic and Instrumentation Engineering, Computer Engineering, Computer Science and Information Technology Engineering. This book also serves as a textbook for B.Sc (Electronics), M.Sc (Electronics), M.Sc (Applied Physics), AMIE, Grad. IETE and diploma courses and as a useful reference for competitive examinations. The material presented in this book describes the classical methods of design technique. With the advent of Integrated circuits and especially the introduction of microprocessors, microcontrollers, microcomputers and various LSI components, the classical method that was predominant in the past for describing the operation of digital circuits, seems to be far removed from practical applications. Although classical method of describing complex digital systems is not directly applicable, the basic concepts of Boolean algebra, combinational logic and sequential logic procedures are still important for understanding the internal construction of many digital functions. The philosophy of this book is to provide strong foundation of basic principles through classical approach before engaging in practical design approach and the use of computer-aided tools. The book is enriched with numerous examples and their solutions. With the clear understanding of basic concepts, the utilization of practical design technique and design software become meaningful and allows the students to use them more effectively.