Google has made a major change to its search algorithm which should push quality sites up the rankings and penalise those that are not useful or copy content from others.

Google's sweeping change will affect 11.8 per cent of its queries and the company insists that the changes will help boost a 'healthy web ecosystem'.

"Many of the changes we make are so subtle that very few people notice them," blogged Google fellow Amit Singhal.

"But in the last day or so we launched a pretty big algorithmic improvement to our ranking - a change that noticeably impacts 11.8% of our queries - and we wanted to let people know what's going on."

Low-quality fall

Singhal continued: "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," he added.

"At the same time, it will provide better rankings for high-quality sites - sites with original content and information such as research, in-depth reports, thoughtful analysis and so on."

The company is 'very excited' about the change, believing it to be a big step in the right direction, as it looks to fend off competition from the likes of Bing and stave off rising criticism of the quality of its search results.

"We can't make a major improvement without affecting rankings for many sites," added Singhal.

"It has to be that some sites will go up and some will go down. 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.

"Therefore, it is important for high-quality sites to be rewarded, and that's exactly what this change does."

UK coming

The changes are currently US only but Google is planning to roll it out in the UK going forward.

With Google ranking a massive factor in internet traffic, the search giant faces an eternal battle against those that try to trick the algorithm in order to move up.

Google is well aware that people want to see websites producing quality, original and useful content at the top of the rankings.