Basically, it generates relevance estimates for webpages based on the topology of links and the pattern of content in the pages.
Now, this doesn't mean that it checks the WWII vet's website against other sources and determines if it is consistent. Rather, it uses it's algorithm to find "good" web sites, and uses link and content patterns to take "good" web sites and spread the "good"ness to other websites.
22/7 wrote:like the number of hits that site receives
Google has very little, if any, knowledge of how many hits a given website receives.
22/7 wrote:What you wrote here has *nothing* to do with what I wrote above it. I was commenting on the statement that I quoted, about how, according to you, the reason that wiki articles tend to come up at the top of a google search is because they're so relevant. It's not, it's because they've paid to be there
Google does not use how much money a website pays them to determine if the website is valid. You can buy ads, but those place you in a different area of the page than the search results. Despite your accusation, Wikipedia does not show up high on the Google search page because it pays to be there.
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The core of the google algorithm involves large matrix multiplication. To do "basic" googling (circa 1995), you create a billion by billion matrix of the internet. Each column/row pair is a specific website. Insert 1s whenever a website links to another website. Raise the ridiculously huge matrix to a reasonably high power (say, 10).
You now have "how many ways can you reach this website using 10 steps of links". This is a first-approximation attempt at determining how linked-to a website is.
Now, there is more than this going on. You have anti-google-bait technologies (aimed at detecting google-bombing). You have term-word specific relevance. You have "store the entire internet in memory", which lets it display the context of the words you searched for.
There are also index biasing strategies (changing which websites are walked by google spiders) which have an impact on the results of google.
The context of each link is also taken into account in ways I do not know enough about. But it means that if enough people say "the greatest evil on earth" and link to microsoft, searching for the "greatest evil on earth" will get you the microsoft homepage.
The goal of all of this work is to use the decision to link as a form of "vote of confidence" in a website. When I'm talking about, say, WWII, I'm more likely to link to a WWII wiki article than the website of a holocaust revisionist. That indicates, as one small bit in a sea of data, that wikipedia (the WWII website) is a decent place to find out information about WWII.
If Wikipedia sucked and I knew of other sources that where better, I would might link to those other sources instead of Wikipedia. Wikipedia being more known would stay at the top -- but as more people learned about the alternative source and it's quality (assuming they agree with me), the number of links pointed at the alternative source would climb.
And that is an example of a "I vaguely understand how Google page rank works" level of understanding. Notice that I made lots of caveats -- I don't know how many parts of the Google engine work.

