Points   A point defines a single location in space. A point geometry does not have length or area. A point always has an X and Y coordinate.

ST_Dimension returns 0 for non-empty points.

In GIS data, points are typically used to represent locations such as addresses, or geographic features such as a mountain.

See ST_Point type.

Linestrings   A linestring is geometry with a length, but without any area. ST_Dimension returns 1 for non-empty linestrings. Linestrings can be characterized by whether they are simple or not simple, closed or not closed. Simple means a linestring that does not cross itself. Closed means a linestring that starts and ends at the same point. For example, a ring is an example of simple, closed linestring.

In GIS data, linestrings are typically used to represent rivers, roads, or delivery routes.

See ST_LineString type.

Polygons   A polygon defines a region of space. A polygon is constructed from one exterior bounding ring that defines the outside of the region and zero or more interior rings which define holes in the region. A polygon has an associated area but no length.

ST_Dimension returns 2 for non-empty polygons.

In GIS data, polygons are typically used to represent territories (counties, towns, states, and so on), lakes, and large geographic features such as parks.

See How polygon ring orientation works and ST_Polygon type.

Circularstrings   A circularstring is a connected sequence of circular arc segments; much like a linestring with circular arcs between points.

See ST_CircularString type.

Compound curves   A compound curve is a connected sequence of circularstrings or linestrings.

See ST_CompoundCurve type.

Curve polygons   A curve polygon is a more general polygon that may have circular arc boundary segments.

See ST_CurvePolygon type.

Geometries   The term geometry means the overarching type for objects such as points, linestrings, and polygons. The geometry type is the supertype for all supported spatial data types.

See ST_Geometry type.

Geometry collections   A geometry collection is a collection of one or more geometries (such as points, lines, polygons, and so on).

See ST_GeomCollection type.

Multipoints   A multipoint is a collection of individual points.

In GIS data, multipoints are typically used to represent a set of locations.

See ST_MultiPoint type.

Multipolygons   A multipolygon is a collection of zero or more polygons.

In GIS data, multipolygons are often used to represent territories made up of multiple regions (for example a state with islands), or geographic features such as a system of lakes.

See ST_MultiPolygon type.

Multilinestring   A multilinestring is a collection of linestrings.

In GIS data, multilinestrings are often used to represent geographic features like rivers or a highway network.

See ST_MultiLineString type.

Multisurfaces   A multisurface is a collection of curve polygons.

See ST_MultiSurface type.