Dozens of so-called "content farms" aim to attract traffic by producing web pages designed to rank highly when users search for common or topical words. Google said that such "shallow" material can be "not very useful" for users.
The firm said the "major improvement" in its search algorithms will instead favour "original content and information such as research, in-depth reports, thoughtful analysis and so on".
"It is important for high-quality sites to be rewarded, and that’s exactly what this change does," Google engineers said in a blog post.
To begin with, the changes will apply to search results for US users only only, with the rest of the world to follow later. Around 12 per cent of queries will be affected, Google said.
Demand Media, the leading content farm, which plans a multibillion-dollar IPO this year, said it had seen some of its pages' search rankings relegated and some promoted as a result of Google's action.
Full story at: The Telegraph