Search engine, relevance means more than just finding a page with the right words. In the early days of the Internet, search engines did not go much further than this simple step, and search results were of limited value. Over the years, engineers have found better ways to link results to search queries. Today, hundreds of factors influence relevance according to Delkn SEO company in Toronto http://www.delkn.com/seo.html
Search engines usually assume that the more popular a site, page, or document is, the more valuable the information they contain. This assumption has been quite successful in terms of user satisfaction with search results.