How Google’s Algorithm Works

Filed in Google, SEO by Matt McGee on February 23, 2010 4 Comments

Google logoI sometimes struggle to explain Google’s ranking algorithm to small business owners. I just tried last week during a workshop here in my hometown, and I’m not sure if I did a good job. But fortunately there are other resources out there that do a better job than me.

One is this new article from Wired magazine: Exclusive: How Google’s Algorithm Rules the Web. Here’s a good portion of it:

Take, for instance, the way Google’s engine learns which words are synonyms. “We discovered a nifty thing very early on,” Singhal says. “People change words in their queries. So someone would say, ‘pictures of dogs,’ and then they’d say, ‘pictures of puppies.’ So that told us that maybe ‘dogs’ and ‘puppies’ were interchangeable. We also learned that when you boil water, it’s hot water. We were relearning semantics from humans, and that was a great advance.”

But there were obstacles. Google’s synonym system understood that a dog was similar to a puppy and that boiling water was hot. But it also concluded that a hot dog was the same as a boiling puppy. The problem was fixed in late 2002 by a breakthrough based on philosopher Ludwig Wittgenstein’s theories about how words are defined by context. As Google crawled and archived billions of documents and Web pages, it analyzed what words were close to each other. “Hot dog” would be found in searches that also contained “bread” and “mustard” and “baseball games” — not poached pooches. That helped the algorithm understand what “hot dog” — and millions of other terms — meant. “Today, if you type ‘Gandhi bio,’ we know that bio means biography,” Singhal says. “And if you type ‘bio warfare,’ it means biological.”

It’s not too technical for me, which means it shouldn’t be too technical for anyone. Highly recommend reading this, not for specific SEO tips but just because the more you understand about how search engines work, the more likely you’ll be able to succeed in increasing search visibility.

One more thing: This Wired article is similar to a series of articles that BusinessWeek ran a couple months ago. I recapped those articles on Search Engine Land, along with links to read each one. Also recommend reading those articles and interviews.

Comments (4)

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  1. A.S. says:

    Thanks for the article Matt! There has been a long time people saying search engines index and rank pages based on relevance. My observations revealed that relevancy can be many types! It can be based on the search term found in a document or in the URL or many times I saw Google ranking pages with the appropriate labels inside them. What say?

  2. David Breth says:


    Your site is one of the most concise and relevant I have found in regard to “proper” SEO and Google’s Algorithm.

    Thank you for the time and insights you consistently give to this most often discombobulated subject.

  3. Angus says:

    It’s pretty amazing how complex Google’s algorithm is. This is just one facet of it, yet there are probably hundreds of other little things it does that are just as amazing, but we’ll never know about most of them…

  4. Elizabeth says:

    Thanks Matt. The Wired article was great. I read an entire book dedicated to the Google Algorithm and even with a math degree on my side I got mired down with all the equations. It is truly an amazing system.

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