Abstract

Online socio-technical systems can be studied as proxy of the real world to investigate human behavior and social in-teractions at scale. Here we focus on Instagram, a media-sharing online platform whose popularity has been rising up to gathering hundred millions users. Instagram exhibits a mixture of features including social structure, social tag-ging and media sharing. The network of social interac-tions among users models various dynamics including fol-lower/followee relations and users ’ communication by means of posts/comments. Users can upload and tag media such as photos and pictures, and they can “like ” and comment each piece of information on the platform. In this work we inves-tigate three major aspects on our Instagram dataset: (i) the structural characteristics of its network of heterogeneous in-teractions, to unveil the emergence of self organization and topically-induced community structure; (ii) the dynamics of content production and consumption, to understand how global trends and popular users emerge; (iii) the behavior of users labeling media with tags, to determine how they de-vote their attention and to explore the variety of their topical interests. Our analysis provides clues to understand human behavior dynamics on socio-technical systems, specifically users and content popularity, the mechanisms of users ’ in-teractions in online environments and how collective trends emerge from individuals ’ topical interests. 1.