In linear algebra, **dimension** is a quantity ascribed to vector spaces. Specifically, it is the cardinality of any basis (a linearly independent and spanning set) of the space. Since the cardinality remains invariant under choice of basis of a given vector space, this quantity is well-defined.

In topology, dimension may refer to any of several intrinsic properties ascribed to objects. Informally, dimension may be thought of as the minimum number of real-valued coordinates necessary to specify a particular point in a given space.