PostGIS (/ˈpoʊstdʒɪs/ POST-jis) is an open source software program that adds support for geographic objects to the PostgreSQL object-relational database.

PostGIS follows the Simple Features for SQL specification from the Open Geospatial Consortium (OGC).

[2] The PostGIS implementation is based on "light-weight" geometries and indexes optimized to reduce disk and memory footprint.

Using light-weight geometries helps servers increase the amount of data migrated up from physical disk storage into RAM, improving query performance substantially.

In 2006 the OGC registered PostGIS as "implement[ing] the specified standard" for "Simple Features for SQL".