Google makes many changes to their algorithm annually (reported to be around 500+ or so a year), but the past 2 years have had two significant updates: Panda and Penguin. With the most recent Penguin update to their algorithm, we’ve seen some websites...
From the horse’s mouth, Google plans on making it’s normal 1/2 a grand in changes this year to it’s search algorithm. “Overall, our advice for publishers continues to be to focus on delivering the best possible user experience on your websites...