This book will help students, practising engineers and engineering managers to understand the basic principles of reliability - what it means, how it is measured, how it is specified. Using a minimum of mathematics, key ideas are explained and illustrated in a practical way. Students and practitioners will find what they want to know: definitions, simple theory, practical advice and exercises (with solutions). The designer will find out how to use both hardware and software failure rates and the project manager will learn about the pitfalls of reliability demonstration testing. The background to the theory and practical examples is largely taken from electrical and electronic engineering, but the basic theory and practical advice are relevant to all forms of engineering.