This book is designed as a reference for the students of Bachelor of Science, Computer Application, Information Technology and Master of Computer Application for the various Universities. This covers all the basic topics of Digital Electronics, which is required for a new comer to understand the subject in an easy and well manner way. To know the different number systems used in Electronics some typical problems also splved, so not only the students but also the teacher and professors can use this book to teach the subject in a better way.