According to the media agenda setting theory I will write about in this thesis, the media are the ones who decide which news and topics will be represented in the audience and they are the ones who can turn that news into extremely important at a certain moment. In this way, the media not only influence the content to be presented, but also public opinion. Numerous changes in setting the media agenda occur with the emergence of online media and social networks. The aim of this work is to show the changes that occur with the emergence of new media and modern society. The rise of new media also brings changes, not only in the theory of the media agenda but also in journalism. Journalism had to adapt to the new online environment and thus adapt information to its new audience. There is also a convergence and merging of different communication platforms, which not only leads to the integration of already existing media, but also to transformation into completely new forms. As time passes by, traditional media, newspapers, TV, radio stations began to lose their main role in the theory of the media agenda, but they are still extremely important to a certain audience, namely that audience that does not trust new media and online journalism. The most important advantage of online media is: the speed of reporting and the possibility of refreshing the content. This thesis also presents research that influenced the development of agenda-setting theory, of which the research conducted by McCombs and Shaw stands out. Some recent research shows significant changes in media agenda theory in the age of social media. The audience becomes a very important agenda-setting resource.