The main provisions, concepts and definitions of information security (IS) of the company, its various structural formations, organizational and legal, technical, methodological, software and hardware support . are presented. Particular attention is paid to the problems of methodological support for the activities of both society and specific systems (OS, DBMS, computer networks) operating in organizations and firms . Real examples describe cryptographic methods and software and hardware tools to ensure information security, their protection against radiation, viral infection, destructive software actions and changes. At the end of each section, control questions are given to check the quality of the students' assimilation of the proposed material . Conforms to the GEF of the latest generation. For undergraduate students studying in the field of software, computer engineering and automated systems, specialists in information technology and information security, a wide range of users of computer systems . It will also be useful for students and postgraduates of higher educational institutions, regardless of their future specialization.