This book covers digital electronic fundamentals, a few integrated circuits, digital devices which include programmable logic devices, microprocessors and microcontrollers. These are essential to electronic engineering, computer science and information technology students at diploma, undergraduate and graduate levels in training institutions, colleges and universities, hence this book is a course book for students or professionals taking digital electronics. It has seventeen chapters. Chapter one(Basic electricity principles;chapter two (Number systems; chapter three(Number Coding; chapter four(Digital Arithmetic; chapter five(Logic families) chapter six (Boolean Algebra; chapter seven(Arithmetic Circuits) chapter eight(Flip flops); chapter nine (Integrated circuits); chapter ten (Multiplexers and de-multiplexers); chapter eleven (programmable logic devices); chapter twelve (Counters and Registers); chapter thirteen (Microprocessors); chapter fourteen (Microcontrollers); chapter fifteen (Introduction to Computers); chapter sixteen (Troubleshooting digital devices) and chapter seventeen (Test equipment's for digital devices. Detailed topics on digital electronics are covered here.