Instinctually, people know what a neighborhood is and most people have a mental map of their own neighborhood, which is very similar to that of their neighbors, even if the neighborhood does not have formal “declared” boundaries. Neighborhoods vary in size, but the most sustainable urban neighborhoods are scaled to human interaction at an easily walkable scale, which means they are confined to a specific geographic area. That does not mean there is no overlap between neighborhoods; there often is at the edges, particularly where there is a common geographic feature like a commercial area, a minor arterial, or a civic space like a park. Nodes and corridors help to center and shape a neighborhood and connect it to other neighborhoods.