72 search engine optimizers from around the world have contributed to SEOmoz’s latest Search Engine Ranking Factors report, a study that offers valuable insight into how SEO works in 2009 … but also shows how little it’s changed in recent years.

Participating SEOs completed a lengthy survey earlier this year that involved ranking possible factors that Google uses when ranking sites. The survey also included a variety of questions about current SEO trends and topics.

According to this year’s survey, the top five ranking factors are:

  1. Anchor Text from External Links
  2. Keyword Use in Title Tag
  3. Raw Link Popularity
  4. Diversity of Linking Domains
  5. Keyword Use in Root Domain

Those first three factors are unchanged from the 2007 version of this survey, although the order is slightly different. Two years ago, the top five were:

  1. Keyword Use in Title Tag
  2. Global Link Popularity of Site (”Raw Link Popularity” above)
  3. Anchor Text of Inbound Links (”Anchor Text from External Links” above)
  4. Link Popularity within the Site’s Internal Link Structure
  5. Age of Site

It looks like SEOmoz changed the structure of this year’s survey a bit. Negative ranking factors are presented separately, and there’s a new chart of “Overall Ranking Algorithm” elements. In fact, the fifth factor on the 2007 list, “Age of Site,” is now essentially the same as (or at least very similar to) the number one piece of the Overall Ranking Algorithm, “Trust/Authority of the Host Domain.”

When it comes to the big picture of SEO, the primary factors really haven’t changed much over the years. But what separates “good” SEO from “great” SEO is often in the details. That’s where you’ll find the true value of the SEO factors survey — in learning the little things that competitors may have overlooked.