Content on a website that was posted by users and not a centralized publisher. This includes social media posts as well as blogs wikis podcasting images videos audio files and other forms of media created and posted by users of an online system or service. Some sites support user content through advertising. Others are supported by donations subscription fees or a combination of methods. Examples of sites that emphasize or are built around user-generated content include Tumblr Facebook Twitter Instagram Pinterest Wikipedia YouTube Vine and SoundCloud.