The textbook is designed to study the theoretical foundations of computer science and master the skills of using information technology. The publication contains basic information about the purpose and subject of the computer science course, its main components and tasks to be solved. The textbook includes an overview of the technical support of electronic computers used in everyday life. The publication also contains descriptions of modern software, including operating systems and application programs. Additionally, the textbook describes the main issues of algorithmization and programming. The publication contains basic information about methods of collective information processing and computer networks, as well as related problems of protecting information from unauthorized access and destruction, including viruses. Practical work on a personal computer has applied value, covering a variety of exercises that can be used to independently master PC skills.