Google has made a major change to its search algorithms in order to try to scrub more link farm results from appearing near the top of search results.

The search and advertising giant tweaks results all the time, but said these changes would hit 11.8 per cent of results, and so it wanted people to know what is going on.

The company said: "This update is designed to reduce rankings for low-quality sites – sites which are low-value add for users, copy content from other websites or sites that are just not very useful."

Results almost always contain at least one or two links to pages that have merely scraped content from other sites based on "hot" search terms likely to attract people from search engines.

The company said the list was not based on the Chrome browser blacklist extension. But it did compare what sites people chose to block via the extension and what websites its algorithms were identifying as crap sites.

Looking at the top few dozen sites which people chose to block from their search results, the algorithms caught 84 per cent of them, which Google described as "strong independent confirmation of the user benefits".

So far the changes are US-only, but will be rolled out worldwide if all goes well.

The page for Google's statement on algorithm changes is here.

Searchengineland has analysis of the changes here. ®