Since Jocelyn Bell saw the first record of radio pulses as a mysterious ‘piece of scruff’ on a chart recording, bringing the neutron star from a remote world of theory into reality, we have been able to investigate the structure of the insides and the outsides of neutron stars in astonishing detail. Neutron stars are seen to be an essential component of the Galaxy, both in the young stellar population concentrated towards the plane and in the extended population of older stars. We now have proof of their origin in supernova explosions, and we have good evidence of their evolution in binary star systems. The combination of pulsars and binary X-ray sources has opened a whole new branch of astrophysics concerned with accretion onto condensed stars and the evolution of binary systems.
Pulsars have provided an entirely new means of investigating the interstellar medium, measuring the total electron content through dispersion, irregularities in electron density through scintillation, and the magnetic field through Faraday rotation. The millisecond pulsars have provided celestial clocks of unparalleled regularity, enabling the most sensitive tests of gravitation theory to be made. Building on these successes, the field of pulsar research has widened and become even more active, extending to the whole electromagnetic spectrum. Radio remains the most productive spectral region, but there has been a revolutionary advance in high-energy gamma-ray pulsar astronomy with the advent of the Fermi LAT satellite telescope.