The thesis deals with the question of the purpose and importance of ethical hackers and ethical hacking, as well as information security, which is closely related to this highly valued and necessary profession. Ethical hackers are people who possess a set of knowledge from various areas of IT in order to perform system checks and analyze vulnerabilities as efficiently as possible. The ultimate goal of ethical hackers is to increase the security of organization's systems, prevent unauthorized access to data, compile architecture and principles, organizational structure and hierarchy of working with data. Distribution of authority considering the fact that man is the biggest threat to information security. With their reports and findings, they inform experts in the field of information security what to focus attention on and what patches to make, about the threats and vulnerabilities of the system, how many threats exist, what are the priorities for solving them and how critical are the vulnerabilities. Ethical hackers simulate attacks within certain limits, depending on the scope and permissions granted to them by the organization, that is, access to the system itself, because they are not malicious, but do a legal job imitating the illegal actions of malicious hackers. The work touched upon various topics closely related to this occupation, with which these experts must be thoroughly acquainted and understand them in order to perform security checks as efficiently as possible. The thesis describes topics such as common types of attacks when hacking systems, the consequences of such attacks and their categories. The importance of cryptography and data encryption and the avoidance of certain protocols, the simulation of network flow, the packet flow and the execution of some of the attacks using certain tools are described. The importance of prevention in crucial time period and risk reduction, depending on the vulnerability. Also are mentioned operating systems with which ethical hackers must be familiar. The occupation described in this thesis requires will and effort, analytical thinking, resourcefulness and readiness for constant learning. The purpose of this paper is to bring this interest closer and explain the need for ethical hackers and their crucial role within the organization.