The topic of the final theses is "Security and Data Security in the Information System". This paper describes the ways of information protection, and the dangers that can threaten and destroy data. In the 21st century, the economic prosperity of the nations and their ability to successfully participate in regional and global integration depends primarily on their ability to protect vital private, business and state data without jeopardizing the privacy of citizens, productivity of the economy and the work efficiency of state organs. Data protection can be defined as a set of methods, techniques and legal norms that restrict access to data by programs and people, and protect the physical integrity of the entire computer system. A large number of documents represent some kind of intellectual property and business secret and require the highest possible level of supervision and protection of access to the document as well as disposal of its content. Many security mechanisms such as antivirus programs, computer security protocols (for example IPSec), access control, encryption, watermarks can be used to protect documents. However, effective protection does not only apply one solution, but a combination of these protection methods. The basic form of defense against viruses and other harmful threats in the information system is computer protection. It is a rather complex procedure that, apart from applying the appropriate programs, requires cautious behavior of the user.