Web 2.0 refers to the participatory web where users can interact and collaborate to share content online. It involves the rise of social media, user-generated content, and Web-based communities. This document discusses how Web 2.0 enables users to actively engage with information through blogs, wikis, social bookmarking, photo sharing, video sharing, and social networks. It explains how libraries can use these Web 2.0 tools to better interact with patrons, create and share content, and participate in online knowledge communities.