Spin evolution of neutron stars in accretion powered pulsars

This is a review of our understanding of the evolution of the spin periods of neutron stars in accretion‐powered binary x‐ray pulsars during the course of evolution of these binary systems. I discuss how neutron stars born in binaries as rotation‐powered pulsars are initially spun down by electromagnetic and plasma torques, until accretion of matter from the companion star begins. I describe how accretion torques spin up and spin down the star during the main x‐ray emission phase of neutron stars accreting from disks, winds, or equatorial rings produced by mass loss from their companions. I outline the final phase of spinup of the neutron stars into recycled rotation‐powered pulsars.