OpenStreetMap

OpenStreetMap (OSM) is a collaborative project to create a free, editable map of the world, built and maintained by a global community of volunteer contributors. Unlike proprietary mapping services, OSM releases its data under an open license, making it the foundational layer for countless geospatial applications. The project's Nominatim geocoder runs on PostGIS, demonstrating that open geographic data and open geospatial infrastructure can be composable rather than monolithic.

OSM's data model — nodes, ways, and relations — is a Vector Data Model that encodes geography as topology rather than as imagery. The radical claim of OpenStreetMap is not that volunteers can produce accurate maps; it is that the world's geographic infrastructure should be a commons rather than a commodity.