One of the most popular applications on Facebook is the Photos application, where users can upload albums and photos. Facebook allows users to upload an unlimited number of photos, compared with other image hosting services such as Photobucket and Flickr, which apply limits to the number of photos that a user is allowed to upload. However, users are limited to 60 photos per album. Privacy settings can be set for individual albums, limiting the groups of users that can see an album. For example, the privacy of an album can be set so that only the user's friends can see the album, while the privacy of another album can be set so that all Facebook users can see it. Another feature of the Photos applications is the ability to "tag", or label users in a photo. For instance, if a photo contains a user's friend, then the user can tag the friend in the photo. This sends a notification to the friend that they have been tagged, and provides them a link to see the photo.
Facebook Notes was introduced on August 22, 2006, a blogging feature that allowed tags and embeddable images. Users were later able to import blogs from Xanga, LiveJournal, Blogger, and other blogging services.[18] During the week of April 7, 2008, Facebook released a Comet-based instant messaging application called "Chat" to several networks, which allows users to communicate with friends and is similar in functionality to desktop-based instant messengers.