Nobody really knows how search engines rank websites for a particular search by a particular user in a particular place. But Google has created a 'nifty' infographic website to help understand it - at least what they are willing to disclose. Be sure to click everything that is clickable so you can see it all.
And if you have questions or want to discuss what this all means for your organization's website call us. We are always up for an SEO discussion - yeah, we are kindof wierd like that.
Here is the How Google Works site.