In mathematics, a Radon space, named after Johann Radon, is a topological space such that every Borel probability measure on M is inner regular. Since a probability measure is globally finite, and hence a locally finite measure, every probability measure on a Radon space is also a Radon measure. In particular a separable complete metric space (M, d) is a Radon space.
References
Radon space Wikipedia(Text) CC BY-SA