The book Digital Logic Design was written to try and solve some of problems faced by students in computer engineering, computer science and electric engineering programs. In most developing countries, there is a scarcity of affordable well written books in information technology especially digital logic design. Digital computers are implemented on digital logic circuits so their design require a good knowledge of digital logic circuits. We the authors of this book are lecturers with many years of lecturing experience at universities and really know the problems faced by studying information technology. This book is organized in form of lectures from the number systems, Boolean algebra up to computer registers. This helps the students understand how a system operates. In the lectures we have included activities and self-assessment exercise to keep the student engaged and also evaluate him/her self. This book is very helpful to both full-time students, those students studying online as well as those on distance.