Driven by the growing popularity of sites such as del.icio.us and Flickr, an increasing number of internet users are tagging content on a daily basis.

A December 2006 survey by research house Pew Internet & American Life Project has found that 28 per cent of US internet users have tagged or categorised content online such as photos, news stories or blog posts.

On a typical day online, seven per cent of internet users say they tag or categorise online content, the researchers said.

"Just as the internet allows users to create and share their own media, it is also enabling them to organise digital material their own way, rather than relying on pre-existing formats of classifying information," the organisation said.

The survey picked up on the growing use of tagging on sites such as del.icio.us, Flickr, YouTube and Technorati.

"Tagging is gaining prominence as an activity which some classify as a Web 2.0 hallmark, in part because it advances and personalises online search. Traditionally, search on the web (or within websites) is done by using keywords, " Pew stated.

"Tagging is a kind of next-stage search phenomenon: a way to mark, store and retrieve 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 report believes that taggers look like classic early adopters of technology. They are more likely to be under age 40 and have higher levels of education and income.