This document introduces the concepts of Library 2.0 and Web 2.0. It discusses how Web 2.0 focuses on communication, collaboration and social interaction between users through technologies like wikis, tags, blogs and social networks. It then explains how Library 2.0 aims to modernize libraries by encouraging two-way interaction between libraries and users, adopting these Web 2.0 technologies to become more user-centered and participatory. Examples mentioned include tagging library catalogs, instant messaging, Facebook groups and using platforms like YouTube, Skype and Wikipedia.