Users can tag URLs ( on del.icio.us ), photographs ( on flickr.com ) soundsamples ( freesound project ) and undoubtedly a myriad of other online objects. Online this creates a open structure of information about information otherwise known as metadata, but what happens offline? How can things in the real world be democratically defined?
The Physical Metadata project attempted introducing tagging into the real world. 55 words were printed on cards (tags, really) and could be attached to real objects in the physical world. More examples of what happened can be seen on www.flickr.com/photos/tags/physicalmetadata.