This paper is primarily concerned with the questions of models and the mechanisms of radio emission for pulsars, the polarization of this radiation and related topic. For convenience and to provide a more complete picture of the problems involved, a short summary of the data on pulsars is also given. Besides the introduction, the paper contains the following sections:(2) Some Facts about Pulsars. (3) The Astrophysical Nature of Pulsars. (4) Coherent Mechanisms of Radio Emission from Pulsars. (5) Models of Pulsars: Magnetic, Pulsating White Dwarfs and Neutron Stars. (6) The Polarization of the Radio Emission from Pulsars. (7) A Synthesized Model of Pulsars — Magnetic, Pulsating and Rotating Neutron Stars. (8) Concluding Remarks.