Tagging, the emblematic activity of the 'Web 2.0' and social computing era, appears destined for mainstream status, a new study concludes.

28 per cent of US internet users have tagged content online, such as blog entries, photos, websites, video clips and news articles, The Pew Internet & American Life Project reports in its latest study (PDF). On any particular day, 7 per cent of users engage in this activity to categorise and label material they upload or find on the web.

Justen Deal, a manager in Los Angeles who tags news articles on sites like Slashdot, believes that as the use of tagging increases, it will give blogging and the web in general a significant boost by making content easier to organise and discover.

"Right now we have one great big pile of stuff on the web, and especially in the blogosphere," he wrote in an email interview. "With tagging, both by the content author and the public, I think there'll be a good opportunity to start moving content into more specific, relevant piles, that would help make sorting through the blogosphere a lot easier and a lot more useful for a lot of people."

Because this is Pew's first survey about tagging, the study doesn't quantify how fast tagging adoption is growing, but it points at the rising popularity of tagging sites like Digg, Flickr and del.icio.us as an indicator that the practice is increasing in popularity.

Jill Hurst-Wahl, president of Hurst Associates, a digitisation consulting firm in New York, began tagging about a year ago and finds it very useful and convenient. Recently, she has attended conferences in which attendees agree to tag their blog postings and photos about the event with specific labels. This has made it possible for her to find a wealth of material online from conference attendees in a way that would have been impossible, or at least much more difficult, without tagging.

While she finds encouraging the 28 per cent adoption rate the study reveals, Hurst-Wahl still encounters many people who are completely unfamiliar with the concept of tagging, or who, ironically, do tag, but don't recognise the term or fully comprehend the scope of the practice. "To some extent tagging is user friendly but a lot of people don't understand it," she said in a phone interview.

Tagging is catching on as people realise the convenience of categorizing sites and files online, and as large internet players like Google Inc and Yahoo Inc, which owns Flickr and del.icio.us, offer tagging features in their services, like webmail, search, photo and video sharing and social bookmarking, according to Pew.

"The act of tagging is likely to be embraced by a more mainstream population in the future because many organisations are making it easier and easier to tag internet content," the report reads.

By giving people the chance to organise online content they're interested in and sharing it with others, tagging helps with the perennial challenge of finding useful things on the web. "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," the report reads.

For its study, Pew surveyed adult US residents in December 2006 and found that men and women are equally likely to tag content online. "Taggers" are more likely to be under the age of 40, to have high education and income levels and to have broadband internet access at home.