The material presented in the textbook covers a wide range of issues in the field of operating systems, computer science and system software. Theoretical materials, practical works, test questions and test tasks are combined, the basic concepts and definitions are emphasized. The sections are presented in a compressed, but at the same time understandable form. Recommended for independent, remote and direct training. The textbook is intended for a wide range of readers: from beginners in the study of operating systems and software to specialists in the field of information and communication technologies.