Web 2.0 refers to changes in how people use the web, moving from static pages to interacting with and modifying information. Common Web 2.0 tools include wikis, which allow collaborative editing; blogs, which are personal online journals; and social networks, which enable online communities. Examples include Wikipedia, Facebook, Flickr, and Ning. Open source software makes the source code publicly available for free use or modification, exemplified by tools like OpenOffice, Moodle, and Portable Apps.