Search engines determine relevancy of your website in the Algorithms:

Major search engines as become smarter they have started using the user’s relevancy of your website in their advance algorithms. The recent algorithms updates give impetus to go away from the most optimized websites to give way for websites that give real value to its customers. These algorithms have become smarter and are giving accurate information for the surfers. This does not mean the other factors like link popularity, keyword density and all other optimization techniques are gone, they are the No1 factors for optimization but what I want to say is search engines are focusing more on relevancy of the website and user experience on your site.

Gone are the days of keyword stuffing or mass reciprocal linking. All search engines Hail the content. It is true as one of the articles in SEO Chat mentions about it. "Content is the thing that customers need in order to make an informed purchase." Also these content rich websites are the sites who get maximum on ROI and more site visitor’s conversion rate.

So the bottom-line is keep updated and change the optimization techniques and marketing styles according how the search engine think.