One thing which many SEO’s tend to do is a search on site:website.com (for example on this site) within Google to see which pages are indexed by Google. It can give you a nice insight in how many pages are indexed and if there are any pages indexed you wouldn’t want to be there. Combined with a keyword you can also see which pages are ranking for that specific keyword. It can also help with determining if your titles and descriptions are right (as you can see I have some work to do).
If you do that search, you will get a list of pages indexed by Google. But how are those pages ranked? Why are they placed in that order? This was the question sent in to Google Webmasterhelp and answered by Matt Cutts. It turns out there are several reasons for why a page is placed in the rankings:
Google tries to surface those pages which are useful or interesting to the searchers. Cutts warns: don’t tread this as a perfect list, even though it does give you an indication of how important Google thinks the page is. See the entire video here: