This document discusses the definitions and history of Web 2.0 and Library 2.0. It outlines the key characteristics of Web 2.0 including being a platform, democratic, interactive, using folksonomy, and prioritizing services over products. Important Web 2.0 sites from 1995-2007 are listed. Library 2.0 is defined as making library spaces more interactive, collaborative, and driven by community needs through blogs, events, and shared content. Both cheerleaders and critics of Web 2.0/Library 2.0 are mentioned. Practical applications for libraries are focused on building relationships, knowing users, differentiating essential and non-essential tools, and training/advertising new services. Examples of tools used