5th edition, revised.

The subject of the theory of equations of mathematical physics is the study of differential, integral and functional equations that describe various natural phenomena. The exact scope of this discipline, as is usually the case, is quite difficult to determine. In addition, the wide variety of issues related to the equations of mathematical physics does not allow them to be covered in any complete way in a university course. The contents of this book constitute only part of the extensive theory of equations of mathematical physics. It included only what seemed to us the most important for an initial acquaintance with this theory.