The book "High Power Microwave Devices: Modeling & Simulation" is aimed at young researchers who wish to engage in the modeling of high-power microwave devices using Particle-in-Cell (PIC) codes or are just beginning to do so. It offers a clear and precise presentation of the subject matter and is designed to introduce readers to both the fundamentals of PIC coding and the various application possibilities. The book includes valuable supplementary material that enables quick learning and application of the concepts. The informative and coherent structure of the text helps readers develop a solid understanding of modeling and simulation in this specialized field.