“If the photo-sharing site Flickr is any indication, the world of digital photographers is dominated by cat people. Dog owners would probably object. But because of Flickr’s tagging system, which allows the photographers or other users to assign identifying tags to most photos on the service, we know that Flickr hosts 23,081 images tagged with ‘cat’ or ‘cats’ and only 17,463 with ‘dog’ or ‘dogs.’ Clearly, Flickr’s system was not set up to motivate a feline-canine supremacy contest. But it does illustrate the way thousands of the service’s members use tags to give some contextual meaning to more than 3.5 million pictures that might otherwise get lost in the shuffle.”