Electromagnetic field and electromagnetic wave are theoretical knowledge about electromagnetism. Around the origin and application of Maxwell equations, it generally includes electrostatic field, steady current field, constant magnetic field, time-varying electromagnetic field, plane wave, waveguide foundation, antenna foundation and so on. From simple to complex, from static to time-varying, from electric field and magnetic field to electromagnetic field, from theory to application, the origin, development and application of electromagnetic field theory are expounded in depth. It is the basis of the follow-up study of microwave and antenna theory. For electromagnetism in college physics, it is a relatively simple explanation of electromagnetism, and it is also based on Maxwell equations, but it is far less systematic, detailed, comprehensive and profound than the former. Compared with electromagnetic fields and electromagnetic waves, the electromagnetic part of college physics focuses on the introduction of concepts and explains the origin of Maxwell equations to beginners, without involving specific applications. Although the analysis method introduces field theory, it is mainly based on algebra, while electromagnetic field and electromagnetic wave are purely theoretical analysis based on field. (Bibliography: Feng Enxin's Electromagnetic Field and Electromagnetic Wave, Wu Baishi's College Physics, xidian university Lecture Notes) qijun00 1