Web 2.0 refers to a second generation of web development that aims to facilitate communication, sharing, and collaboration online through services like Google, Wikipedia, and blogging, rather than packaged software. Key aspects of Web 2.0 include harnessing collective intelligence through user-generated content, lightweight user interfaces, and software that works across devices. Examples of Web 2.0 technologies discussed in the document include blogs, wikis, podcasts, webcasts, social networking sites, RSS feeds, and collaboration sites like Google Docs and Wikispaces.