Tagging tends to refer to activities such as social bookmarking where users rather than administrators, authors or taxonomists provide metadata for purposes of navigation or search.

Folksonomy is a practice of collaborative categorization using freely chosen keywords. More colloquially, this refers to a group of people cooperating spontaneously to organize information into categories. In contrast to formal classification methods, this phenomenon typically only arises in non-hierarchical communities, such as public Web sites.