Sarah Holder:

“For most of human history, maps have been very exclusive,” said Marie Price, the first woman president of the American Geographical Society, appointed 165 years into its 167-year history. “Only a few people got to make maps, and they were carefully guarded, and they were not participatory.” That’s slowly changing, she said, thanks to democratizing projects like OpenStreetMap (OSM).
 OSM is the self-proclaimed Wikipedia of maps: It’s a free and open-source sketch of the globe, created by a volunteer pool that essentially crowd-sources the map, tracing parts of the world that haven’t yet been logged. Armed with satellite images, GPS coordinates, local community insights and map “tasks,” volunteer cartographers identify roads, paths, and buildings in remote areas and their own backyards. Then, experienced editors verify each element. Chances are, you use an OSM-sourced map every day without realizing it: Foursquare, Craigslist, Pinterest, Etsy, and Uber all use it in their direction services.
 When commercial companies like Google decide to map the not-yet-mapped, they use “The Starbucks Test,” as OSMers like to call it. If you’re within a certain radius of a chain coffee shop, Google will invest in maps to make it easy to find. Everywhere else, especially in the developing world, other virtual cartographers have to fill in the gaps.