A spatial relation specifies how some object is located in space in relation to some reference object. Since the reference object is usually much bigger than the object to locate, the latter is often represented by a point. The reference object is often represented by a bounding box (oblique or axis-parallel).
In Anatomical terms of location|Anatomy it might be the case that a spatial relation is not fully applicable. Thus, the degree of applicability is defined which specifies from 0 till 100% how strongly a spatial relation holds. Often researchers concentrate on defining the applicability function for various spatial relations.
In spatial databases and Geospatial topology the spatial relations are use for spatial analysis and constraint specifications.
Commonly used spatial relations are: topological, directional and distance relations.