Bruce Sterling on folksonomy in Wired

Wired Magazine April 2005: Order Out of Chaos

There's a revolution going on in the art and science of categorization, and its name is folksonomy, a term term invented by information architect Thomas Vander Wal.
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A folksonomy... arises spontaneously as Net users encounter information, think about what it means, and tag it with descriptive words. Then software makes the information accessible via a simple keyword search. The results aren't definitive or scientific, but they can be very useful.