The emergence in the scientific community of an initiative known as data sharing, consisting of sharing research data among researchers and aiming to maximize efforts and resources, is analysed. First, the concept of research data and the related technical difficulties depending on the discipline are reviewed. We also examine the motivations, origins and growth of this movement, which has had an important impact on the scientific community’s behaviour through the creation of reposi- tories and data banks, raising both technical and social challenges. Then we discuss leading funding agencies’ initiatives and scientific journals’ editorial policies promoting these practices. Finally, we examine the impact these major changes in researchers’ habits have for librarians, including the emergence of new professional profiles.