TIMING NOISE AND GLITCHES

One of the most remarkable properties of radio pulsars is their rotati onal stability which allows many uses as clocks. For instance they ena ble us to determine the shapes and sizes of binary orbits, to study ge neral relativistic effects in strong gravitational fields, to demonstr ate the existance of gravitational radiation from binary systems, to p ermit the detection of extra solar planets, and also to put limits on the long period gravitational wave background. However, some display t iming imperfections which tell us about the insides of neutron stars. This review describes the basic physics of slowdown and how period ins tabilities seem to be related to the rate of slowdown and the presence of internal superfluid liquid. Careful studies of glitches and the su bsequent rotational behaviour of the pulsars can provide valuable info rmation on the internal structure of neutron stars.