This paper provides an introduction to Spectrum Management with a DoD perspective. It assumes the audience is unfamiliar with radio communications theory, with the current allocation and use of spectrum, and with the processes involved in managing spectrum. Therefore, it begins by providing an introduction to basic concepts in radio communications theory in order to build the novice's intuition so that he might subsequently understand the rationale for the current allocations and the methods for managing spectrum. It attempts to give a historical record of how these processes and allocations came to be. It describes the current spectrum management process to include the major players and the procedures they use to make decisions. Finally, it gives a brief introduction to some new technologies that are being introduced and their ramifications on the spectrum management process. Thus, this paper has been written as both a tutorial and a basic reference for new players in the spectrum management business.