Today's electronic era has brought many changes to all aspects of human life, including both the private and the business sphere. The amounts of data created, stored, shared and updated on a daily basis is continually increasing, and both the users and the data they share have come to the forefront of the company's interests to improve the quality of their business. Big data is the notion of the huge amounts of this data that represent the material for analysis in order to make better decisions and strategies of the institution itself. Although this term is most often associated with companies and profits, libraries are an important link between other institutions and the public, and therefore generate many important data. Since it is difficult to process them using standard tools, librarians should be able to analyze them and make them more accessible and more user-friendly according to trends. This paper deals with the notion of big data and its theoretical and practical application in libraries. The aim of this paper is to outline the applicability of big data technologies in libraries, and the opportunities and disadvantages of this trend within the library industry through the analysis of other scientific papers.