Einstein’s special theory of relativity provides a unique insight into the fundamental properties of the electromagnetic field. It presents, from a new perspective, the intimate connections among the E, D, H, B fields and their sources-connections that we have heretofore examined only through Maxwell’s equations. To appreciate the simplicity and beauty of electrodynamics in the context of special relativity, one must first learn the language of tensor analysis, which is where this chapter begins. From there we move to a description of the flat, four-dimensional spacetime of H. Minkowski, and the transformation rule, named after H. A. Lorentz, that governs coordinate transformations among different inertial reference frames. We proceed to describe the electromagnetic fields and their sources as seen by different observers in uniform unaccelerated motion relative to each other, thereby uncovering some of the most intriguing features of classical electrodynamics.