PostGIS is a spatial database extender for PostgreSQL object-relational database. It adds support for geographic objects allowing location queries to be run in SQL.
In addition to basic location awareness, PostGIS offers many features rarely found in other competing spatial databases such as Oracle Locator/Spatial and SQL Server.
Refer to PostGIS Feature List for more details.
PostGIS is released under the GNU General Public License (GPLv2 or later). Refer to License FAQ for more information. PostGIS is developed by a group of contributors led by a Project Steering Committee.