This book provides an important link between the theoretical knowledge in the field of non-linier physics and practical application problems in microelectronics. It delivers different levels of understanding of the physical phenomena that play a critical role in limitation of the semiconductor device capabilities, physical safe operating area limitation, and different scenarios of catastrophic failures in semiconductor devices. The book focuses on power semiconductor devices and self-triggering pulsed power devices for ESD protection clamps. The purpose of the book is popularization of the physical approach for reliability assurance. Another unique aspect of the book is the role of local structural defects, their mathematical description, and their impact on the reliability of the semiconductor devices. One of the major challenges the book covers is the gap in understanding of major physical regularities between the theoretical knowledge in the field of non-linier phenomena in semiconductors and the reliability and ESD protection problems in process and device development, circuit design, TCAD, and applications.