This comprehensive book describes the science of functional verification that applies to any digital hardware system. With a precise terminology the book describes a thorough technical framework for achieving superior results with greater efficiency. It also defines a scientific basis for achieving functional closure and shows how true functional closure can be measured by software. The author provides a wealth of practical guidance to the practicing professional. He describes how to compare results from differing projects and how to assess the risk of functional bugs at tape-out or at any other critical product juncture. The book also shows consumers how to compare IP offerings from multiple vendors. For producers, it describes how to verify IP in a manner that meets customer needs. This is a valuable reference for verification engineers and managers. The principles and theory this book describes will drive creation of the next generation of verification tools.