The practice allows sites to differentiate between the web pages that are seen by normal users and those that are scanned by search engine spiders – programs that assess and rank web sites. In effect, the cloaked pages are bypassed by normal viewers, but boost the site's ranking because of their additional content.
According to Google's web site, the practice is prohibited because it "can mislead users about what they'll find when they click on a search result." Google also warns, "To preserve the accuracy and quality of our search results, Google may permanently ban from our index any sites or site authors that engage in cloaking to distort their search rankings."
So Google took note last week when anti-spyware campaigner Ben Edelman alleged that WhenU was using at least thirteen cloaking sites in "an attempt to hold multiple positions in search engine results bearing WhenU's name". Users clicking on links to these sites from search engine results were taken not to the sites originally scanned by the search engine, but to different pages containing pro-WhenU news stories.
Both Google and Yahoo! have now removed the direct link to the adware company from their databases.
According to CNET News.com, WhenU's CEO Avi Naider has blamed the practice on an external search engine optimisation firm.
"The moment we were alerted to this today, it was taken down," Naider explained on Thursday. "We anticipate being re-listed in the major search engines soon."