This chapter provides a brief presentation of Maxwell’s equations, assuming that the bases of electromagnetics (EM) are already known. The main idea is to recall the principal concepts necessary to the work developed afterward. EM can be described by the equations of Maxwell and the constitutive relations. The EM phenomena associated with the magnetodynamic field can be very complex. There are basically two types of magnetic materials: soft magnetic materials and hard magnetic materials. Soft magnetic materials include diamagnetic, paramagnetic, and ferromagnetic materials, while hard magnetic materials include permanent magnets. In soft magnetic materials, the situation is approximately the same; however, the application of a weak external magnetic field in the direction opposite to the internal field is sufficient to eliminate the remnant flux density, as opposed to the situation in permanent magnets. A diamagnetic material is placed under the influence of a uniform field. The chapter also presents an overview of the key concepts discussed in this book.