Do you know that search engines, in particular Google, keep on evolving their technology to provide better user experience and results? They invested millions of dollars and employed thousands of people because they feel that they want to keep spam at bay.
Being a market leader in the Search industry, Google is putting in their maximum efforts to maintain the lead over the other search engines such as Yahoo! and Bing by rolling out frequent algorithm changes. In 2010 alone, there were more than 500 updates done. Which means to say we’re looking at between 1-3 updates on every singel day. More importantly in 2010, the Panda update was incorporated.
When you are looking for an SEO provider, do ensure that they are not practising any forms of black hat SEO. If they do, the sites often got impacted with frequent Google updates and thus, in the long run, their ranking would not be ideal. It is advisable to look for a reliable firm that practises white hat SEO. Proper SEO companies keep pace with evolving search technology and they use and employ the right methods and strategies to improve your site traffic and conversion.
Here is a video on how vigorously Google updates their algorithm.