By MIGUEL HELFT
IF you know what you’re looking for online, Google and other Internet search engines do a pretty good job of helping you find it. But what if you don’t know exactly what you want?
Say you are a soccer fan, but you are neither in the market for new cleats nor in search of the buzz on Greg Ryan, the coach of the United States women’s team. Instead, you just want to see interesting soccer sites. Googling “interesting soccer” or “great soccer stuff” is not likely to be satisfying.
A Web service called StumbleUpon has spent the last six years trying to satisfy such a need, perfecting a formula to help you discover content you are likely to find interesting. You tell the service about your professional interests or your hobbies, and it serves up sites to match them. As you “stumble” from site to site, you will feel as if you are channel-surfing the Internet, or rather, a corner of the Internet that is most relevant to you.
Web discovery, or search without a query, is still a niche activity, but StumbleUpon’s growth to 3.5 million registered users from 600,000 two years ago suggests it is on a path to becoming more mainstream.
“We’ve seen over the last few years a growing population of people who are online and aren’t exactly sure what they’re looking for,” said Michael Buhr, the general manager of StumbleUpon. “That’s what discovery is about.”
Here is how StumbleUpon works: You can use the service directly from its Web site, but for the fullest experience, you’ll want to download its Internet browser toolbar, register and check categories that interest you — say, parenting, the environment or yoga, or all of the above. Then, each time you click on the Stumble toolbar icon, the service shows you sites in those categories that other users have found interesting. You can stumble through a single category or across all your interests. You can choose to view any kind of Web site or just photos or videos.
StumbleUpon has about 12 million sites in its database, a sort of “best of the Web” compiled by users of the service. You can influence that collection by giving a thumbs up or thumbs down to any Web site. The service uses that information — and similar data gathered from the 7.5 million “stumbles” its users perform each day — to keep refining what may be interesting to individual users, based on their shared interests and other characteristics.
StumbleUpon borrows from two ideas that are familiar to millions of Web users. One is collaborative filtering, the technology used by Amazon.com to recommend books based on what you and others have bought. The other is social networks like Facebook and social sites like Digg or del.icio.us, where users vote on the most popular news stories or share interesting sites.
StumbleUpon is different in its combination of computer-generated and human recommendations and its application of the technology to the entire Web. And though, over the years, it has added social features like personal Web pages for users and the ability to communicate and share sites with friends, it can be used simply to discover interesting stuff.
“If I took half an hour to search the Web in a normal way, I may find one or two sites that are interesting to me,” said Trevor Joyce, a user from Cork, Ireland, whose interests include poetry and photography. “If I use StumbleUpon, I get 10 or 20.”
Web discovery is catching on. Google uses a version of it, called “push search,” to help users add content to their iGoogle pages, home pages that can be personalized with information and services from the Web. And Google recently rolled out a service called Dice, which, much like StumbleUpon, recommends Web sites. Dice’s recommendations are based on your past searches, not on others’ suggestions.
“Right now, the primary way that people look for information is traditional search, by a large margin,” said Sep Kamvar, the engineer leading Google’s personalization efforts. “However, iGoogle is the fastest-growing product at Google. That suggests that push search and discovery of information without a query is becoming more and more important to people.”
Underscoring Google’s bet that discovery is poised for a growth spurt, the company tried to buy StumbleUpon this year, people familiar with the discussions said. Several others, including AOL and various venture capitalists, were also interested in the service. In May, eBay delivered the winning bid — $75 million — for StumbleUpon.
EBay plans to keep StumbleUpon independent and continue to operate it as a standalone service. Over time, it plans to let users stumble through eBay’s vast database of items up for auction.
STUMBLEUPON makes money by charging Web sites that want to be included in its database or want to be shown to users more often. For now, these sponsored sites make up only a small portion of all the sites shown. The company won’t disclose how often it inserts sponsored sites, which are identified by an uninformative green icon on the toolbar depicting the head and torso of a person. (Rolling the cursor over the icon will tell the user that it is a sponsored site.) But in a nonscientific test across various categories, that icon appeared fewer than once every 25 stumbles.
Because users can give those sites the thumbs up or down, StumbleUpon will become better and better at matching ads with users, said Garrett Camp, 28, who, with two friends, founded it while he was a graduate student in Calgary, Alberta. For now, the company, which has fewer than 20 employees, is not profitable, Mr. Buhr said.
In recent months, StumbleUpon has added the ability to stumble through specific sites, including Wikipedia, Flickr, YouTube, TheOnion.com, CNN.com and PBS.org.
It is when you are stumbling through YouTube or through Web videos in general that the StumbleUpon experience most resembles the TV remote — though one that tries to serve up programming to match your interests and whose suggestions get better with time.
That is one reason Mr. Camp is confident that StumbleUpon, or some other discovery service, will become a Web-wide hit over the next few years, as people increasingly shift their consumption of media to online from offline. “People aren’t going to stop channel surfing just because they don’t have a TV and they have laptops instead,” he said.