This is a list of phenomena specific to the Internet, such as popular themes and catchphrases, images, viral videos and more. Such fads and sensations grow rapidly on the Internet because its instant communication facilitates word of mouth. In the early days of the Internet, phenomena were primarily spread via email or Usenet discussion communities. Today, many of these phenomena are also spread via popular, user-based or social networking Web sites, including (but not limited to) 4chan, Digg, Facebook, Fark, Flickr, Myspace, Slashdot, Something Awful, or YouTube. Search engines, such as Google, Yahoo, or Bing may also amplify the propagation of these phenomena.