Covers the state of the art and the full spectrum of topics in defect diagnosis ranging from the basic concepts, real world application to future challenges. After a brief review of the basic concepts and applications of diagnostics over the life-cycle of a product, the established diagnosis procedures will be discussed, including fault dictionaries, post-test fault simulation, and hardware-based backtracking. Next, recent enhancements and advanced diagnosis topics will be covered, including methods for locating defects such as opens, shorts, and leakage in transistor-level circuits, approximation techniques for identifying unmodelled faults, deductive analysis, Iddq-based diagnosis, diagnosis for delay-faults, Scan-chain diagnosis, BIST-based diagnosis, and design-for-diagnosability techniques. A focus on Silicon debug techniques, design-for-debug techniques, and applications to yield improvement will follow. Successful diagnosis methods used in real industrial products, industrial experiences and case studies will be described, as well as future challenges.