This paper focuses on Information Warfare—the warfare characterised by the use of information and communication technologies. This is a fast growing phenomenon, which poses a number of issues ranging from the military use of such technologies to its political and ethical implications. The paper presents a conceptual analysis of this phenomenon with the goal of investigating its nature. Such an analysis is deemed to be necessary in order to lay the groundwork for future investigations into this topic, addressing the ethical problems engendered by this kind of warfare. The conceptual analysis is developed in three parts. First, it delineates the relation between Information Warfare and the Information revolution. It then focuses attention on the effects that the diffusion of this phenomenon has on the concepts of war. On the basis of this analysis, a definition of Information Warfare is provided as a phenomenon not necessarily sanguinary and violent, and rather transversal concerning the environment in which it is waged, the way it is waged and the ontological and social status of its agents. The paper concludes by taking into consideration the Just War Theory and the problems arising from its application to the case of Information Warfare.