Web map tiles—the storing of geospatial data at different zoom levels in x/y/z indexed squares of raster (and later, vector) data for efficient storage and transmission of digital maps—are, despite their seeming simplicity, I think one of the most significant developments in geospatial software history. Tiling transformed the user experience of digital maps from one of tedious clicks-and-reloads to one of fluid, dynamic exploration. It made digital maps feel spatial, an interface that one litera...