Tagging or labelling online content is becoming the new search tool of choice among web users, shows research.
Flickr users can sort content via their tags
As more and more people put their own content online, they are also being invited to tag it with descriptive keywords to help organise their data.
According to the Pew Internet and American Life Project, the trend in tagging is growing among US web users.
It found that over a quarter of online Americans - 28% - had tagged content such as a photo, news story or blog.
The business of intelligently tagging content is seen as a crucial element for a next-stage, so-called "semantic web".
But for users of social networking sites it is just an obvious tool to navigate around the sites they visit.
Tagging is the process of creating labels for online content. Somebody creating an account on a site such as Flickr is invited to upload photos and then apply labels to the pictures that make sense to them - for instance, labelling a picture of the sun going down as "sunset".
Once the labels are applied, anyone entering the term "sunset" into Flickr's search will find the photo and any other pictures with the tag.
In this way, tagging makes it easier to organise information for all the users of a site and this social dimension means tagging is becoming a hallmark of the so-called web 2.0 - the social networking element to the net that encourages sharing and collaboration.
Tagging comes in many forms. Google's tagging feature is called "bookmark", while other sites offer the ability to label content so effortlessly that people may not be aware they are doing it.
David Weinberger, a fellow at Harvard's Berkman Center for Internet and Society and a prominent blogger, told Pew that tagging was becoming increasingly important for the web.
Mr Weinberger makes the case for tagging in his book Everything is Miscellaneous: The Power of the New Digital Disorder.
This new way of organising information in the digital age, he argues, is a classic example of how the web is enabling the bottom-up building of categories rather than having such things imposed on users.
"Tagging lets us organise the vastness of the web, and even our e-mail, as Gmail has shown, using the categories that matter to us as individuals," he said.
Some have criticised tagging as being too imprecise or ambiguous but Mr Weinberger is not concerned that one person may tag, say, a Stephen King story as "horror" while someone else calls it "ghost story".
"Tagging allows social groups to form around similarities of interests and points of view. If you're using the same tags as I do, we probably share some deep commonalities," he told Pew Internet.
Data from web-tracking firm Hitwise shows that tagging sites such as Flickr and del.icio.us - a bookmarking site that lets users tag websites with descriptive terms - are gaining popularity as people become more aware of them.