search engine optimization, "off page" factors have become more and more important as they relate to rankings. In particular, solid link popularity can literally make or break a site with the search engines.
Before we go any further, what is "link popularity"? In very simplistic terms, link popularity refers to the number and quality of the incoming links that are pointing to your site. These other sites consider your site important enough to link to. So, in the engine's view, your site is considered important as well. What is meant by "link popularity" can get much more complex, which is discussed further in this article.
However, one of the most difficult areas of SEO is building link popularity. Why? Because the engines don't want "artificially created" (or useless) links, so there are no easy ways to build link popularity. The days of link farms and huge link exchange programs are over. Try those strategies now and you can easily find yourself booted out of an engine.