# Geographic functions

Geographic functions work with coordinate pairs and typed coordinate collections. Use a consistent coordinate system for each calculation.

## Function families

* [Geographic distances](https://coordinatordb.com/docs/reference/functions/regular-functions/geo/coordinates) measures a spherical arc from longitude/latitude coordinates and returns metres.
* [Geometry construction](https://coordinatordb.com/docs/reference/functions/regular-functions/geo/geometry) creates Point, Ring, Polygon and related aliases with validated nesting.
* [Point in polygon](https://coordinatordb.com/docs/reference/functions/regular-functions/geo/polygon) tests containment with defined outer-boundary and hole rules.

The geometry aliases do not assign a coordinate reference system or validate polygon topology. See [geometry types](https://coordinatordb.com/docs/reference/data-types/geometry-types) for shapes and [GeoJSON](https://coordinatordb.com/docs/reference/formats/geo-json) for importing and exporting features.