  Almost 50 years after radio pulsars were discovered in 1967, our
understanding of these objects remains incomplete. On the one hand, within a
few years it became clear that neutron star rotation gives rise to the
extremely stable sequence of radio pulses, that the kinetic energy of rotation
provides the reservoir of energy, and that electromagnetic fields are the
braking mechanism. On the other hand, no consensus regarding the mechanism of
coherent radio emission or the conversion of electromagnetic energy to particle
energy yet exists. In this review, we report on three aspects of pulsar
structure that have seen recent progress: the self-consistent theory of the
magnetosphere of an oblique magnetic rotator; the location, geometry, and
optics of radio emission; and evolution of the angle between spin and magnetic
axes. These allow us to take the next step in understanding the physical nature
of the pulsar activity.
