YouTube, which bills itself as "your digital video repository," allows web surfers to upload videos to the site and tag them. The videos can then be shared openly with the public or privately shared only with friends and family. People can search the site to see the videos open to the public. For example, here are all the videos tagged under "dog." The website also listed the most popular and the most discussed videos. YouTube says it accepts video files from most digital cameras and from cell phones in the .AVI, .MOV, and .MPG file formats.