The range of tasks for the dynamics of rarefied gases includes tasks on the flow around aircraft moving at high altitudes, on the movement of gases in vacuum apparatus, ultrasonic vibrations in gases, the structure of shock waves, non-equilibrium currents, etc. This monograph deals mainly with problems that require kinetic description, for the solution of which gas dynamics methods are not applicable and new methods, approaches and images are needed. The main place is given to the Boltzmann kinetic equation, the study of its properties and solution methods.