Milestones of general relativity: Hubble's law (1929) and the expansion of the universe

Hubble's announcement of the magnitude-redshift relation \cite{Hub29} brought about a major change in our understanding of the Universe. After tracing the pre-history of Hubble's work, and the hiatus in our understanding which his underestimate of distances led to, this review focuses on the development and success of our understanding of the expanding universe up to the present day, and the part which General Relativity plays in that success.