This video from Matt Cutts clears this confusion.
Question: How Does Google Separate Simple Popularity from True Authority?
Answer: “From the earliest days, it would get us really frustrated when we saw reporters talk about Page Rank and say that Page Rank is a measure of the popularity of the website…because that is not true! For example, if you were to look at sites that are popular, well. for example, XX sites are very popular but people tend not to link to them. On another hand, if you take something like the Wisconsin real estate board, probably not a ton of people go there but quite a few people link to government websites. So, popularity in some sense is a measure of where people go , whereas Page Rank is much more a measure of reputation, its much more a reputation where people link. There is a disparity there or else XX sites would have the highest Page Rank and government websites would be very very low in our ranking system. That’s not the way things work.
You can separate simple popularity from reputation or authority. But, now, how do we figure out that you are a good match for a given query? Well, in turns out, you can say…take Page Rank for example, if you wanted to do a topical version of the Page Rank, you could look at links to a page. You can say suppose its Matt Cutts, how many of my links actually talks about Matt Cutts.If there are a lot of links then I am pretty topical and may be an authority for the phrase “Matt Cutts”.
Also See:
Toolbar Page Rank Update Gradually Fading Down
Google Will Continue to Support Toolbar Page Rank
Author Rank is the New Page Rank
Rel = “Author” – An Important Ranking Signal for Google
What are Doorway Pages?
Keyword Stemming
How to Find Out Which Keywords You Rank For
New Google Ranking Factors
Top Factors for Local Listing
Adding Ratings and Review Stars on Search Results
