Editor's note: This article is a sidebar to Cracking Google's 'secret sauce' algorithm.
Just when search engine optimization experts think they've got the PageRank algorithm figured out, Google makes another change, and those changes can throw online businesses that rely on search engine traffic for a loop.
"Sometimes there's a big change and everybody goes berserk," says Atul Gupta, president and CEO of RedAlkemi. "Unfortunately, Google tends to play these tricks on you. They'll change the algorithm 15 days before Christmas. All those people who've based their calculation on sales on free traffic, suddenly have to go [back to the drawing board]. They've done that more than once, so site owners are a bit weary. But if you deploy good, safe techniques, our clients do not suffer."
Looking ahead, Google is going beyond site links to determine popularity, and is beginning to study the user behavior of visitors to reward or devalue sites. They gather this information in several ways. Web users who install the Google Toolbar agree that some information can be captured and forwarded to Google. If a user does a search and clicks on the third entry in the search results, Google records that the user preferred the third link rather than the first or second. It's also recording how much time a user spent on a particular site. Google can also record the computer's cache where temporary data is stored. "If you're revisiting sites, they're also recording that," Gupta says. "If it's sticky enough, they must be doing something good on that site, so they'll push up the ranking."
With more than half of its traffic coming from outside the U.S., Google is also working on algorithms that offer personalized content by geographic region, so a Web user in the U.K. who searches "football" will turn up information on soccer and not the NFL. "Now we might get a lot of e-mails because if you were No. 1 for football [search rankings] before and now you're No. 1 in the U.S and not in the U.K., you might not be happy about that," says Matt Cutts, senior engineer at Google.
Collett is a Computerworld contributing writer. Contact her at email@example.com.