This article briefly reviews our current understanding of the evolution of
magnetic fields in neutron stars, which basically defines the evolutionary
pathways between different observational classes of neutron stars. The emphasis
here is on the evolution in binary systems and the newly emergent classes of
millisecond pulsars.Comment: Has appeared in Journal of Astrophysics and Astronomy special issue
on 'Physics of Neutron Stars and Related Objects', celebrating the 75th
birth-year of G. Srinivasa