Changes at Google mean that stale website content will be penalised – and that means organisations wanting a high ranking on Google may need to change their ways.

The latest  update is designed to analyse whether a person wants up-to-date results or historical data.And Google estimates the alterations to its core ‘algorithm’ would make a difference to about 35% of searches.

The update to improve the “freshness” of results builds on a large-scale update made to the underlying infrastructure of Google’s core indexing system in August 2010 known as Caffeine, making it easier for Google to keep its index up to date and to add new sources of information.

Web analysts have described the changes as “huge”. The last big update to the Google algorithm, known as Panda, affected only 12% of searches.

Google Panda was built through an algorithm update that used artificial intelligence in a more sophisticated and scalable way than previously possible. Human quality testers rated thousands of websites based on measures of quality, including design, trustworthiness, speed and whether or not they would return to the website.

Google’s new Panda machine-learning algorithm, made possible by and named after engineer Navneet Panda was then used to look for similarities between websites people found to be high quality and low quality.

Many new ranking factors have been introduced to the Google algorithm as a result, while older ranking factors like PageRank have been downgraded in importance.

One thing is clear; those websites featuring good, regularly-updated copy will be rated more highly by Google. And those that do not will be less visible on the search engine.