"FLICKR"

Flickr asks photo submitters to organize images using tags , which allow searchers to find images related to particular topics, such as place names or subject matter. Flickr was also an early website to implement tag clouds, which provide access to images tagged with the most popular keywords. Because of its support for tags, Flickr has been cited as a prime example of effective use of folksonomy, although Thomas Vander Wal suggested Flickr is not the best example.

Flickr also allows users to organize their photos into "sets", or groups of photos that fall under the same heading. However, sets are more flexible than the traditional folder-based method of organizing files, as one photo can belong to one set, many sets, or none at all. Flickr's "sets", then, represent a form of categorical metadata rather than a physical hierarchy. Sets may be grouped into "collections", and collections further grouped into higher-order collections.