At the end of 2003, Schachter opened a Web site, del.icio.us, to let anyone use the technology. With del.icio.us, people are able to tag any link they choose for easy retrieval later. What makes tags more powerful than a Web bookmark is that they can be shared easily with other people. If someone tags a story on Iraq, for example, that link is added to a list on del.icio.us of other Iraq content. Anyone on the service who wants to read about Iraq can then find a list of stories that have been tagged and see who tagged them. Today more than 85,000 people are using the free service. "Tagging is about the most important tool of last year," says Clay Shirky, an adjunct professor at New York University's Interactive Telecommunications Program.
Indeed, the practice is catching on fast. The blog index Technorati Inc. and corporate portal developer Plumtree Software Inc. (PLUM
) are adopting the technology. Amazon.com Inc. (AMZN
) announced in February an investment in tagging startup 43 Things. And in March, Net giant Yahoo! Inc. (YHOO
) paid an undisclosed sum for Flickr, a year-old photo-sharing service that attributes its success in luring 420,000 subscribers to its use of tagging. While Yahoo won't discuss specific plans, it's expected to sprinkle tagging throughout its Web properties. "I hope [Flickr's co-founders] become part of our vanguard to help us as we venture boldly and somewhat blindly into this [new world]," says Jerry Yang, co-founder of Yahoo.
There's a good reason Yahoo is taking tagging seriously. The trend represents a new approach to organizing and finding information online, and industry watchers expect it to draw people away from the traditional Net search offered by Yahoo and Google Inc. (GOOG
). Tagging won't replace Google et al. But people may turn to tags more frequently over time, reducing their use of established search engines.
The risk? It could cut into the search-advertising revenues that are all-important to Google and Yahoo. No one has estimated the potential toll, but losing even a few minutes of people's time each day could be costly. "Search is no longer the only way to find things," says Howard Rheingold, author of Smart Mobs: The Next Social Revolution.
Search engines, for all their advances in recent years, have a glaring drawback: No matter how many pages they index or how quickly they bring back results, they can't put those results into context. They can find a specific word, but they can't figure out what the word means. An example: Look up the word "python" on Google, and the list of results throws together sites about the reptile, the programming language, even Monty Python. You have to sift through pages of irrevelant results to find what you want. To help avoid the confusion, Web sites often manually label their pages with category titles, a version of tags called metadata. But mass search engines, such as Google, don't use metadata because they can contain spam or misleading descriptions.A "LAYER OF SOCIAL KNOWLEDGE"
Tagging, however, lacks the algorithmic wizardry of search engines. But it lets people work together organically to create the context traditional search typically misses. Blogger Thomas Vander Wal coined the word "folksonomy," a combination of the words folk and taxonomy, to describe this joint work. It's like a grassroots Dewey Decimal Classification System for the Web. The essence: The combined work of people busily tagging content creates another way to make sense of the mountains of information online.
People are using tags to share their work and their whimsies. At del.icio.us, groups are adopting specific tags to help them collaborate on projects. For instance, in January a group of bloggers interested in applying technology to nonprofit groups adopted the "NPTech" tag. They file links to that tag, creating a bibliography of research that contains more than 900 articles, Web links, and blog posts. At Flickr, individuals often create a tag meant to inspire others to take and share photos. An example: Under the "What's in your bag?" label, users have posted photos of the contents of computer bags, knapsacks, and purses. "What has me really excited is this layer of social knowledge that's being created," says David Weinberger, a fellow at Harvard University's Berkman Center for Internet & Society. "We can't even anticipate yet what kind of research we will be able to do or the services that will develop."
The rising popularity of tagging is spurring debate about potential problems. Already, spam is being posted within tags at Technorati. Flickr and Technorati use a combination of automatic filtering and manual removal to combat these early marketing attempts. Still, if spam can't be held in check, it will undermine the usefulness of tags. "Every healthy ecosystem has parasites," says David L. Sifry, founder and CEO of Technorati. "We're trying to take into account what we learned from e-mail spam."
Another worry is whether tagging could collapse under its own weight because it isn't a standardized system created by professionals. In the free-flowing tagging world, one person might apply the tag "camera phone" to photos taken with a mobile phone, while someone else uses the words "mobile phone," undermining the whole point of sharing valued information. People also might use overly broad words as tags, say, Paris or wireless, resulting in too much information to plow through.
Tagging proponents such as Shirky maintain that no one company can afford the cost of applying standard tags to everything on the Web -- that only many individuals tagging every day could help structure the vast reaches of Net content. And these individuals and businesses are devising ways to make it easier to find just the right information via tags. For instance, Technorati recently copied Flickr in offering lists of related tags when someone does a search on a generic one. So while tagging may look unorganized, there is logic to this avalanche of virtual Post-its.
People are providing their own likes and dislikes as guideposts to help others pick their way through cyberspace. Tagging is bringing a new kind of order to the chaos of the Web. By Heather Green in New York, with Robert D. Hof in Scottsdale, Ariz.