Interactions between Electromagnetic Fields and Matter deals with the principles and methods that can amplify electromagnetic fields from very low levels of signals. This book discusses how electromagnetic fields can be produced, amplified, modulated, or rectified from very low levels to enable these for application in communication systems. This text also describes the properties of matter and some phenomenological considerations to the reactions of matter when an action of external fields results in a polarization of the particle system and changes the bonding forces existing in the matter. This book considers the above phenomena in detail by explaining matter as a conglomeration of charged mass points in the electromagnetic field. Quantum mechanics and Maxwell's theory can then account for the precise description of the interactions between the electromagnetic fields and matter. This book then describes special processes such as 1) the static and quasistatic interactions and 2) dynamic processes, particularly the resonance process. This text also defines a general form for electric and magnetic reactions using the generalized field equation. This book also cites the anharmonic oscillator and the single spin as different examples of electric and magnetic dipole interactions. This text is suitable for electrical engineers, radio technicians, physicists whose work is in quantum mechanics, and engineers interested in electro-magnetism theory.