Here is a quick overview of some of the announced Google search algorithm changes that have been made in January and February of this year.
In 2010 there were two major algorithm changes dealing with spammy content. Here we are only two months into 2011 and we have already had two major algorithm changes dealing with the same issue.
The January change was an upgrade to Google’s document-level classifier. This change made it harder for spammy on-page content to rank high.
You can read the accouncement by Matt Cutts on the official Google Blog. Google Search And Search Engine Spam by Matt Cutts.
The sites that were devalued are sites that copy others content, sites with a low level of original content, sites that have poor quality spammy copy. These sites are referred to as content farms.
A week later Matt Cutts noted on this personal blog in an article Algorithm Change Launched that the update that targeted “low levels of original content” was a targeted launch where only 0.5% of serach results change enough to be noticed with the effect being you would see more original content.
In February Google announced from their blog a Personal Blocklist Chrome brower extention where people can block sites from their search results. The personal blocklist extension also transmits to Google the sites you choose to block from appearing in your searches.
Following the Jan 21st algo change there was another announcement made on the Google Blog that was made on Feb 24th called Finding More High Guality Sites In Search. This was a bigger change where over 11% of the queries changed.
While it was bigger it really was just more of the same where they targeted sites that “sites which are low-value add for users, copy content from other websites or sites that are just not very useful”. Also in this algorithm they provided better ranking for sites with “original content and information such as research, in-depth reports, thoughtful analysis”.