It is a pleasure to thank Michael Kramer and Jiannis Seiradakis
for their comments on earlier incantations of this review. Also
thanks to a number of colleagues who have kindly gave permission
to use a selection of figures in this article. Michael Kramer
provided the magnificent animation of the rotating neutron star
presented in Fig.
14, based on unpublished timing observations carried out at Jodrell
Bank, was supplied by Andrew Lyne. Vicky Kaspi provided the
millisecond pulsar timing residuals and comparison of their
timing stabilities shown in Figs.
respectively. Frequent use was made of NASA's excellent
Astrophysics Data System  during the literature searches.