PostGIS adds support for geographic objects to the PostgreSQL object-relational
database. In effect, PostGIS "spatially enables" the PostgreSQL server, allowing
it to be used as a backend spatial database for geographic information systems
(GIS), much like ESRI's SDE or Oracle's Spatial extension. PostGIS follows the
OpenGIS "Simple Features Specification for SQL" and has been certified as
compliant with the "Types and Functions" profile.

PostGIS development was started by Refractions Research as a project in open
source spatial database technology. PostGIS is released under the GNU General
Public License. PostGIS continues to be developed by a group of contributors led
by a Project Steering Committee and new features continue to be added.

WWW: http://www.postgis.org/