It is popular to talk about what a vacuum is, when and how this concept arose and how the vacuum theory developed in the future. Processes on the surface of solid bodies, processes in rarefied gases and some of the processes occurring in the volume of the substance and essential for the operation of vacuum devices and installations are considered. It is told about how vacuum is obtained and measured, about the application of vacuum in technology and science, about the interaction of vacuum technology and vacuum physics with other fields of technology and science. For schoolchildren and teachers.