Social tagging also known as “folksonomies”, are user-defined metadata collections. Users do not deliberately create folksonomies and there is rarely a prescribed purpose, but a folksonomy evolves when many users create or store content at particular sites and identify what they think the content is about. “Tag clouds” pinpoint various identifiers and the frequency of use on a folksonomy site. This type of grass-roots community classification (similar to other social networking approaches, such as blogs and wikis) is subject to vandalism and manipulation; nevertheless, it is a fine example of collective intelligence.Do not confuse folksonomies with taxonomies. Folksonomies structure content via user tags; taxonomies are classifications defined by more formal methods that do not necessarily include user-generated tags and rarely are viewed as similar.