PostGIS is an open-source software extension for the PostgreSQL relational database that adds support for geographic objects, allowing location queries to be run in SQL. It complies with the Simple Features for SQL specification from the Open Geospatial Consortium (OGC). With PostGIS, users can perform spatial queries, analyses, and various geographic operations. This capability makes it a powerful tool for managing and analyzing spatial data in various applications such as Geographic Information Systems (GIS), location-based services, and environmental modeling. The official website is https://postgis.net/, where users can find documentation, downloads, and community support.