folksonomy

n. a collaborative classification system of applying user-created keywords, or tags, to online content to describe and categorize information

Notes

Folksonomy is a portmanteau of folk and taxonomy. However, a folksonomy is not a true taxonomy. Whereas a taxonomy is usually hierarchical, a folksonomy is not. A folksonomy does not use a predetermined system of organization; a taxonomy uses a predetermined system to classify content. Folksonomies do not use an established system for classification determined by one person or group; they are collaborative over time.