This tutorial is based on the course of lectures on "Superconductivity," that the author delivered over the years for senior students of the Institute of Physics, Nanotechnology and Telecommunications in Peter the Great St.Petersburg Polytechnic University. The increased interest in the physics of superconductivity in recent years is due to the discovery in 1986 high-temperature superconductors, which on one hand made it possible for cooling of the superconducting transition to forgo expensive liquid helium but replace it with cheap liquid nitrogen, while on the other hand, raised hopes of observing superconductivity at room temperature. Experimental and theoretical studies of the physics of superconductivity have not only laid the foundation for creating superconductors with necessary technical properties but also have led to a better understanding of different branches of physics. These studies highlighted a number of phenomena, not directly associated with a loss of resistance, such as Meissner and Josephson effects, Shapiro steps, magnetic flux quantization, macroscopic coherence of wave functions, etc. They have given rise to new physical images and concepts: Cooper pairs, Abrikosov vortices, intermediate state, Shubnikov phase –just to name a few. When creating this course the author has aimed to introduce future physicists to these original ideas and images that have enriched not only solid state physics, but all branches of fundamental physics. All measurements are presented using the International System of Units (SI). In some graphs, taken from the original works, there are also the units used in electromagnetism CGS, in particular Gauss and Oersted. Their conversion to the SI is based on the ratio of 1 G =10-4 Tl; 1 Oe=80 A / m. It should be borne in mind that most of the formulas in the CGS system have a different appearance.