The rapid development of technological systems, advances in technology and the increasing number of Internet users poses an increasing threat of cyber attacks. Cybernetics, as a scientific discipline, studies the general principles of management and communication, and is required for information systems to survive. An information system is a part of any business system whose function is a continuous supply of necessary information. This thesis describes terrorism as a global security threat and strategies in the fight against terrorism. The aim of the paper is to present and explain the concept of terrorism, threats to cyber security and how the information society was created and developed, which led to the emergence of computer and cyber crime and its prevention in the Republic of Croatia. Although it is obvious that terrorists are becoming more and more users of computer equipment and the Internet, it is important to point out that not every illegal use of computer equipment is cyber-terrorism in itself. Cyber-terrorism is a fairly new term, which describes the permeation of terrorism and the virtual computer world. It is defined in one sentence as a premeditated, ideologically motivated attack on computer systems, programs, databases and networks, which is carried out with the help of information technology and results in causing fear, violence and great material damage to non-combatant targets, with the aim of influencing on the public and political processes. Put simply, cyber-terrorism is the use of high-tech means against high-tech targets. Today, almost all national legislations recognize the concept of electronic (electronic, digital) evidence and have certain rules governing the ways in which electronic data, i.e. documents, can be used as evidence. The ultimate goal of collecting and analyzing electronic data and creating electronic evidence is their presentation in the evidentiary process. Electronic evidence/documents may be the subject of expert examination, especially with regard to their authenticity, probative value, truthfulness of content and prescribed form.