Google has been tweaking its algorithms (the systems it uses to identify how relevant it's links are to the search terms entered) over the years, with a view to improving the user experience, and promoting results which are more relevant and abide by their recommended guidelines relating to search engine optimisation.

Recently there have been two major updates which have hit some sites particularly hard causing them to drop significantly in major search engines. This article will cover the Google update first seen in February 2011 and later rolled out internationally in August 2011 known as 'Panda' or 'Farmer', and the more recent Penguin update.