Guest editorial: social media in scholarly communication

Social media metrics - commonly coined as "altmetrics" - have been heralded as great democratizers of science, providing broader and timelier indicators of impact than citations. These metrics come from a range of sources, including Twitter, blogs, social reference managers, post-publication peer review, and other social media platforms. Social media metrics have begun to be used as indicators of scientific impact, yet the theoretical foundation, empirical validity, and extent of use of platforms underlying these metrics lack thorough treatment in the literature. This editorial provides an overview of terminology and definitions of altmetrics and summarizes current research regarding social media use in academia, social media metrics as well as data reliability and validity. The papers of the special issue are introduced.