The Pew Internet Project has a good study on the increasing prevalence of tagging.
Just as the internet allows users to create and share their own media, it is also enabling them to organize digital material their own way, rather than relying on pre-existing formats of classifying information. A December 2006 survey by the Pew Internet & American Life Project has found that 28% of internet users have tagged or categorized content online such as photos, news stories or blog posts. On a typical day online, 7% of internet users say they tag or categorize online content.
These people said “yes” to the following question: “Please tell me if you ever use the internet to categorize or tag online content like a photo, news story, or a blog post.” The wording was designed to capture the growing use of tagging on sites such as http://del.icio.us/ (a site for sharing browser bookmarks), http://www.flickr.com/ (a photo sharing site), http://youtube.com/ (a video sharing site) and http://technorati.com/ (the blog search engine).
Tagging is gaining prominence as an activity some classify as a Web 2.0 hallmark in part because it advances and personalizes online searching. Traditionally, search on the web (or within websites) is done by using keywords. Tagging is a kind of next-stage search phenomenon – a way to mark, store, and then retrieve the web content that users already found valuable and of which they want to keep track. It is, of course, more tailored to individual needs and not designed to be the all-inclusive system that Melvil Dewey tried to create with his decimal-based
scheme for cataloguing library materials.
The great thing about tagging is it takes search to the next level. Instead of Google ranking sites by how many inbound links they have, these social bookmarking sites like del.icio.us let average users categorize content in ways that are useful to them. This is a report worth reading if you want to understand some of the trends in internet use.