Google has rolled out the change to its search algorithms that promotes premium over "farm" content, incorporates user feedback and penalises sites blocked by users across all English language websites.
Amit Singhal, on the Google Webmaster Central blog yesterday, said since Google introduced the change in the US last month, it has received "positive feedback" from users reporting better quality search results, with publishers receiving greater traffic.
He wrote: "This change also goes deeper into the ‘long tail’ of low-quality websites to return higher-quality results where the algorithm might not have been able to make an assessment before."
More lower traffic websites, which Google's algorithms may not have been able to assess before, will now be included in the results.
Google claimed the change to the algorithm is "very effective" at detecting site quality. It said any developers, publishers or companies that believe their website is high quality but has been affected by the change should "evaluate different aspects of [their] site immediately" by visiting its quality guidelines.
The change should provide a boost to the websites of traditional publishing houses, some of which have complained over the increasing presence of "content farms", which produce content at a very low cost based on what people are searching for.
Singhal, in a blog post last month that announced the change in the US, said: "Google depends on the high-quality content created by wonderful websites around the world, and we do have a responsibility to encourage a healthy web ecosystem.
Google is currently being investigated by the EU, after several rival search providers complained of unfavourable treatment in Google's results.
In December last year, Google made a change to its algorithms to boost "nicer" websites and penalise sites with poor customer relations.