Pulsars as clocks

Being massive, inert flywheels, spinning in essentially empty space, and whose rotation can be observed, it is not surprising that pulsars are potentially superb clocks. In this review, we describe the technical means by which this promise can be realised in practice and the limitations to their precision as clocks. This is followed by examples of the use of these remarkable astrophysical clocks for studying general relativity and other areas of fundamental physics