Google has changed its secret search formula in the United States to be more discerning when it comes to which websites are worth recommending and which should sink in the rankings.
The move announced late Thursday was part of an ongoing duel between the search titan and low-quality websites that feature only content copied from elsewhere on the Internet or use techniques to trick their way high in results.
"Many of the changes we make are so subtle that very few people notice them," Google principal engineer Matt Cutts and Google fellow Amit Singhal said in a blog post.
"But, in the last day or so we launched a pretty big algorithmic improvement to our ranking."
They said the search formula change affects 11.8 percent of search queries, dropping low-quality websites in results while elevating high-quality websites with original content such as research, analysis, or in-depth reports.
"We do have a responsibility to encourage a healthy web ecosystem," Cutts and Singhal wrote.
"Therefore, it is important for high-quality sites to be rewarded, and that's exactly what this change does."
Google said that it has been working on the issue for more than a year and engineers spent several months crafting the algorithm change, which was implemented in the United States and will be rolled out elsewhere over time.
The change at the world's most popular search engine was a hot topic among website operators on Thursday, with some happy that Google knocked "content farms" down a few notches and others complaining of unfairly dropping in rank.
Content farms are in Google crosshairs because such websites are known to pack pages with copied or superficial material crafted to capitalize on attention-getting topics.
Such websites want to attract as many people as possible in hopes of making money off online advertising.
"They may have whacked eHow good, but they did it in part through a crude duplicate content filter," someone with the online name 'Content ed' said in a busy chat forum at webmasterworld.com.
"I'm seeing long established sites getting killed because they have been ripped-off, copied and rewritten/repurposed to the point that Google can't tell who was the original."
Demand Media runs eHow, answerbag and other websites referred to by some as "content farms" because they are crammed with articles seemingly geared more to score high in search rankings than be top sources of information.
"As might be expected, a content library as diverse as ours saw some content go up and some go down in Google search results," Demand Media executive vice president of operations Larry Fitzgibbon said in a blog post.
"It's impossible to speculate how these or any changes made by Google impact any online business in the long term," he continued. "But, at this point in time, we haven't seen a material net impact on our Content & Media business."
Demand Media websites focus on "useful and original" content, Fitzgibbon maintained.
The Google crackdown comes a month after Demand Media went public with its first offering of stock. Demand Media shares slipped more than three percent to $22.19 per share in late trading on Friday.
Google continually refines its search formula in a quest to deliver more relevant and useful results at faster speeds.
Website operators from the honorable to the nefarious have taken to employing "search engine optimization" tactics such as abundantly repeating popular query terms or fostering high numbers of links to other properties.
While Google keeps its search formula secret, both those factors raise websites in rankings of results.
There is tremendous subjectivity in the debate regarding content farms, and Google is in a difficult position, Greg Sterling of search news website Search Engine Land told AFP.
"Their success has bred a whole industry of freelancers producing articles that are ultimately designed to show display ads and rank highly in search results," Sterling said.
"They feel compelled to address it because they are being criticized by many sides that results are full of spam," he continued. "Google feels that if it doesn't address this, its existence is threatened."
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