Contemporary cartography faces a threefold, simultaneous set of pressures. First, it is clear that a restricted circle of specialists no longer holds a monopoly over cartographic production and that there is no longer any implicit agreement about maps. Secondly, scientific and technological innovations are rapidly modifying the boundaries between what a map is and is not, increasing the importance of the individual user or map maker. Finally there is a great need for cartographic instruments to empower the citizen-cartographers, tools to help them make sense of the maps that they are...