This book discusses the direct imaging of electric and magnetic fields of various functional materials using electron holography, providing indispensable information for understanding their electromagnetic properties. In order to clearly demonstrate the principles of this cutting-edge technology, easy-to-understand explanations are accompanied by numerous illustrations and figures throughout the book. The book highlights the dynamic nature of electromagnetic fields in novel materials, as revealed by changing temperature, or applying electric current and magnetic fields. Furthermore, it showcases, as a new development of the technique, the direct observation of accumulation and collective motion of electrons around charged insulators. Clear experimental data on electromagnetic fields and the motions of electrons help the reader understand their importance in materials science and fundamental physics. Seeing is believing!