Most of the papers included in this volume, except for the editor's introduction, come from the conference on Visual Propaganda and Online Radicalization hosted in 2012 by Georgia State University in conjunction with the U.S. Army War College. They all speak to the power of visual images, particularly in the online environment, and the sophistication with which a variety of extremist and terrorist groups have adapted to the online environment, particularly through the use of powerful visual images. The strategic point made in these essays, and which serves as a unifying theme throughout the collection, is that weaker forces use these materials to great effect, and to even greater effect when we either underestimate the power of visual images or fail to develop effective counters. The unique value offered by these essays is to lay out clearly the ways in which images work for extremist groups, and to begin the process of developing effective strategies for responding. As the editors make clear, there is an extensive literature available establishing that when compared to text (or words heard over an audio track), images are remembered better, over a longer period of time, and with greater emotional power, having commanded more attention initially. This is true for moving and still images.