# Dimension of geometries

A geometry can have a dimension value to indicate whether a geometry is empty or the geometry has a length or area.

The dimensions values are as follows:
-1
Indicates that a geometry is empty
0
Indicates that a geometry has no length and an area of 0 (zero)
1
Indicates that a geometry has a length larger than 0 (zero) and an area of 0 (zero)
2
Indicates that a geometry has an area that is larger than 0 (zero)

The point and multipoint subtypes have a dimension of zero. Points represent dimensional features that can be modeled with a single tuple of coordinates, while multipoint subtypes represent data that must be modeled with a set of points.

The linestring and multilinestring subtypes have a dimension of one. They store road segments, branching river systems and any other features that are linear in nature.

Polygon and multipolygon subtypes have a dimension of two. Features whose perimeter encloses a definable area, such as forests, parcels of land, and lakes, can be represented by either the polygon or multipolygon data type.