In today's digital age, academic libraries increasingly recognize the importance of being present on social networks such as Facebook and Instagram as key tools for promoting their services and resources. This thesis explores how academic libraries utilize digital channels to achieve their missions and goals, focusing on digital marketing strategies, the specifics of nonprofit marketing, and the role of social networks in the library context. The theoretical framework of the thesis covers basic marketing concepts, an analysis of the components of the marketing mix applied in libraries, and digital marketing strategies tailored to the specific needs of users. The empirical part of the thesis analyzes the presence of academic libraries on Facebook and Instagram, with a detailed case study of the most successful libraries such as the University Library of Rijeka, the Scientific Library of Zadar, and the Library of the Faculty of Humanities and Social Sciences in Zagreb. Research results show that libraries actively using social networks achieve significant visibility and user engagement through creative content such as stories, videos, and virtual events. Key factors for their success include adapting strategies based on metric analyses, continuous dialogue with users, and maintaining enthusiasm and innovation in everyday work. This thesis provides valuable insights into the potential of social networks as tools for promoting library services and offers practical guidelines for improving the digital presence of academic libraries. Ultimately, it highlights the importance of further research and the development of strategies that will enable libraries to optimally leverage the advantages of the digital age for better support of the academic community and the general public.