Web search giant Google has confirmed that it made major alterations in its search algorithm to discourage the likes of content farms plus related spammy-content producing sites.

Google said that 11.8 per cent of search queries were updated perceptibly. It means there would be changes in the top two to three search results.

Google made the changes in the search algorithm following criticisms from several users for ranking unhelpful articles high in the search results.

The company claims that it has not made use of user data from a Chrome extension that was rolled out recently to allow users block particular sites in Google results which upset them.

The changes will now improve the ranking of high-quality websites, and will decline the ranking of low-quality websites.

The so-called content farms such as Answerbag and eHow produce articles based on popular search queries so that they can attain high ranks in the search results and gain more and more clicks.