A non-hierarchical keyword or term assigned to a piece of information. This kind of metadata helps describe an item and allows it to be found again by browsing or searching. (Wikipedia)
design, ontologies, technique, collaborative design
Taking tasks traditionally performed by an employee or contractor, and outsourcing them to a group (crowd) of people or community in the form of an open call.
Hypertext Preprocessor, is a widely used, general-purpose scripting language that was originally designed for web development, to produce dynamic web pages.
John Vaughan suggests that "you should check out Geeks Bearing Gifts" because you are interested in Tagging.
Joe Schmo is a highly rated expert in the area of Tagging who recently answered several relevant questions on ALTA.