As the Sun is an ordinary star of our galaxy, then such problems, for example, as energy sources, structure, and spectrum formation are common for the physics of the Sun and stars. Therefore, the whole variety of already established solar phenomena: a granular structure of the surface, complex changes of brightness and motions in its separate active centers, processes in outer rare atmospheric layers, in particular, solar flares, solar prominences, solar wind-are inherent not only in the Sun but in other stars as well. For these reasons, solar physics is of great importance for the development of astrophysics as a whole.