This document discusses the rise and evolution of social networking sites. It provides statistics on usage and growth of major sites from 2005-2008, showing large year-over-year increases initially for sites like MySpace and Facebook. However, starting in late 2007, some sites like Friendster began declining rapidly as users migrated to sites with better features. By 2008, usage of many top sites began leveling off or declining slightly, suggesting the social networking market was becoming saturated. The future of these sites will depend on their ability to continue innovating and retaining users.