Web 2.0 refers to a transition of the World Wide Web from static websites to a computing platform serving dynamic web applications. Key characteristics include harnessing collective intelligence through user contributions, reusing and sharing data, and providing a rich user experience across devices. While some criticize Web 2.0 as hype, others see it as a major change in how information is accessed and shared through tools like RSS, weblogs, podcasts, start pages, bookmarking, search builders, wikis, and instant messaging. These tools support collaboration, sharing, and mashing up information in new ways.