This document discusses how librarians can use social media to benefit library users. It provides examples of how libraries are using social media platforms like Twitter and blogs to market services, answer inquiries from users, and collaborate with researchers. The document also discusses how altmetrics can help measure the broader impact of research by tracking mentions in social networks, views and shares on platforms like YouTube, Mendeley readership, and mentions on blogs and in the press. Altmetrics provide additional context alongside traditional citations for understanding how research is engaging different audiences.