What are Folksonomies?

Definition

The terms folksonomy and tagging are often used interchangeably to describe a social classification process where individuals add keywords (tags) to items, most commonly images, websites, or articles.  These freely-applied keywords are not limited by any categories or hierarchies, and hence tags exist in a "flat name space."³  Initially a person adds tags to better identify or find an item later, but their tagged items and terms also contribute to a larger network of labels and objects identified by other members of the community .  If this definition reads a little rough, it may be beneficial to skim Thomas Vander Wal's concise explanation:

"Folksonomy is the result of personal free tagging of information and objects (anything with a URL) for one's own retrival [sic]. The tagging is done in a social environment (shared and open to others). The act of tagging is done by the person consuming the information."⁴

Folksonomies can been compared to Wikipedia's inclusive and collaborative model of article writing.  Both have been discussed as examples of social software.⁵

Synonyms and the Terminology Debate

The term folksonomy is attributed to information architect Thomas Vander Wal, from the origin "folk" and "taxonomy."  Taxonomy, however, refers to hierarchy whereas folksonomies consider all terms on an equal basis with none greater than any other.  Peter Merholz proposes "ethnoclassification"⁶ as a more appropriate term, but the accuracy of this word has also been questioned.⁷  As Adam Mathes notes, what folksonomies do is closer to categorization than classification.⁸

This terminology debate is likely to remain a theoretical contest.  In common usage the catchiness of folksonomy and intuitiveness of tagging have already won.  For the remainder of this discussion, I will be using folksonomy to refer to systems and tagging to refer to the actions of adding keywords to items.