Abstract: This paper reviews the large and varied body of literature published on the subject of Information Operations (IO) in an attempt to arrive at an understanding of the concept on a theoretical level. Understanding IO requires one to make a fundamental shift in ones understanding of the critical role of information in all its forms in modern societies, and therefore of the potential of information as a powerful tool, or weapon, which can be used to influence others. In an offensive sense, the overall goal is the attainment of information dominance so as to be able to impose ones will upon others. The implications of IO for military forces are also discussed. Although IO is not dependent on IT, IT-dependence is a fact of modern armed forces. The application of IT to military operations combined with the speed of transmission and volume of information available on future battlefields can be expected to blur traditional boundaries of time, space and levels of war, requiring armed forces to modify structures and procedures in order to effectively execute IO. (The incorporation of IO theory into military doctrine and practice will be examined in a subsequent paper.)