Large-scale distributed simulations model the activities of thousands of entities interacting in a virtual environment simulated over wide-area networks. Originally these systems used protocols that dictated that all entities broadcast messages about all activities, including remaining immobile or inactive, to all other entities, resulting in an explosion of incoming messages for all entities, most of which were of no interest. Using a filtering mechanism called interest management , some of these systems now allow entities to express interest in only the subset of information that is relevant to them. This paper surveys ten such systems, describing the purpose of the system, its scope, and the salient characteristics of its interest management scheme. We present the first taxonomy for such systems and classify the ten systems according to the taxonomy. The analysis of the classification reveals the fundamental nature of interest management and points to potential areas of research.