Social media have become firmly established as a new publishing and communication tool with significant value for all the aspects of contemporary society, culture and science. Social media feature a dynamic and continuously evolving nature, fostering the creation and exchange of concepts and ideas in an unprecedented scale. The leading role of social media coupled with the inherent volatility and the ephemeral nature of this medium, compared with other forms of electronic communication, has rendered social media preservation as necessary. It is critical to preserve social media as they are an essential part of our heritage and they can prove valuable for current and future generations. Social media preservation is an advanced topic of digital preservation, encompassing the capture, management, preservation and availability of social media for future use and research. To achieve this goal, we need to advance the state of the art in a wide range of diverse topics such as social media modeling and analysis, classification, information retrieval, content migration, replication, emulation and web preservation strategies. Furthermore, we need to focus not only on theoretical advances but also on innovative applications and systems. In this special issue, we are aiming to exchange the latest fundamental advances in the state of the art and practice of social media preservation and important related areas. In this issue we have included 7 papers, which have been selected out of 17 papers that were submitted in response to our call. Some information about these papers follows. The paper by L. Akritidis and P. Bozanis entitled “Improving Opinionated Blog Retrieval Effectiveness with Quality Measures and Temporal Features” deals with the problem of retrieval of blog entries, which contain opinions about entries by paying special attention to the importance of such entries. The proposed ranking method takes into account the influence of the blogger who authored an opinion, the reputation of the specific blog site and the impact of the blog post itself. Experiments with TREC Blogs08 dataset shows enhancement of retrieval precision. The paper by G. Gkotsis, K. Stepanyan, A. Cristea and M. Joy entitled “Entropy-based Automated Wrapper Generation for Web Data Extraction” focus on the process of weblog data extraction. The approach includes a model for generating a wrapper that exploits web feeds for deriving probabilistically (based on entropy) a set of extraction rules in an automatic way. The World Wide Web (2014) 17:691–693 DOI 10.1007/s11280-014-0282-4