Neutron stars, being the objects of close attention and research interest of physicists and astronomers, are the sources of strictly periodic pulsed radiation. Every neutron star has its own unique characteristics; in particular, a frequency of pulses, radiation spectrum and intensity, glitches and pauses, and all of this together raises many questions:- what is the mechanism of such a behavior;- what is the origine of such differences;- what is the physics of these phenomena in general and what is the dynamics of the processes in individual manifestations;- what changes can emerge in the properties of matter under the extreme conditions that are specific to neutron stars, etc.The investigation of some of these issues is one of the objectives of this book, which has the form of a collection of studies on the physics of neutron stars. Among them, some researches are devoted to the influence of external fields on the properties of neutron stars, and reactions and transformation of the matter in its envelopes and interior layers.