Google makes hundreds of algorithm changes every year and 2011 is no exception. This year, Google made big algorithm changes that affected that search engine rankings of millions of websites.
The first notable algorithm change made by Google was on January 28 when they released an update that focused on weeding out sites that scrape content. This was followed by the First Panda Update on February 23, 2011. Other much-talked about Google algorithm changes include the launch of the Google +1 button and succeeding Panda updates.