This is a comprehensive introduction to our present understanding of the electrical nature of thunderstorms for graduate level students of physics and/or meteorology, as well as research scientists. The text systematically discusses the electrical measurements of storms, examines lightning mapping studies in detail, presents many electrical observations in the context of storm structure and evolution, explains modern numerical cloud models of storm electrification, and examines electrical properties of several types of storms and storm systems. The book details the advances made possible by new technologies in a form that is suitable both for students and for professionals in the field.