"refers to the collaborative but unsophisticated way in which
information is being categorized on the web. Instead of using a
centralized form of classification, users are encouraged to assign
freely chosen keywords (called tags)
to pieces of information or data, a process known as tagging. Examples
of web services that use tagging include those designed to allow users
to publish and share photographs, personal libraries, bookmarks, social software generally, and most blog software, which permits authors to assign tags to each entry."
That's interesting, because for the first time in history, the great masses are in charge of cataloging and definining things. No longer are experts needed to publish great hulking bodies of work to define the human experience for the rest of us. That's pretty exciting.