Understanding the spatial organization of regions in images is a crucial task, essential to many domains of computer vision. The histogram of forces--a quantitative representation of the relative position between two objects--constitutes a powerful tool dedicated to this task. It encapsulates structural information about the objects as well as information about their spatial relationships. Moreover, it offers solid theoretical guarantees and nice geometric properties. Numerous applications have been studied, and new applications continue to be explored. For instance, force histograms can be compared through similarity measures for fuzzy scene matching. They can be used for describing relative positions in terms of spatial relationships modeled by fuzzy relations. They can also be used for scene description, where relative positions are represented by linguistic expressions. This chapter reviews and classifies work on the histogram of forces. It touches topics as varied as human-robot communication and spatial indexing mechanisms for medical image databases.