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How Google Works Part 1 - The Man Behind the Curtain

How Search WorksThis three part series pulls the curtain back on the great Google that we are all using more and more every day. It is a very complicated topic that we (attempt to) simplify.


Google works a lot like a public library, is funded a lot like an old national television broadcaster, and has spun off entire new industries.


In case you haven't been to a library in the last decade or so, here's a refresher. Libraries are large buildings with lots of books in them. So how do you find a book? In the era before computers, you might check the card catalog. Card catalogs categorize by author, title, or subject / keyword. Each card contains information about the book, along with where to find it in the library. The card then includes a short sentence, or sometimes even an abstract or summary of the book. If you want assistance, there is a librarian that is skilled and trained to help you through.


So how does this relate to Google? Well, Google is similar to the librarian with the card catalog. Google's catalog just covers the internet. You give Google some keywords, a subject, or a phrase, and Google gets you a list of website pages they believe match. So the websites are like books, and the website pages are like pages in books. Google searches through its latest catalog of the internet to get your search results.


So how does Google build its catalog? Google has what is referred to as a spider that crawls the web -- their spider is named GoogleBot. GoogleBot starts by cataloging and indexing a single website. Then it looks at the links from that website to other websites, visits each, cataloging and indexing along the way. By doing this, going from one site to another, over and over, GoogleBot can get to much of the internet.


Relating back to books, books may have references to other books or periodicals. With a book, how do I know if it is a good book without reading it? We could judge the quality of the book by it's cover, but that's not very useful. Usually we look for reviews of the book by others we respect. I'd believe a finance book is good if it is well reviewed in the New York Times, but maybe not if the review is from The National Enquirer. Also, if other quality books reference this book, it's more likely to be a good book. Academia and research scientists rely heavily on references. If a researcher wants to be published in a quality scientific journal, they are sure to reference other relevant, quality research. Also, they want other researchers to reference their work. The more quality references to their work, the more prestige they, and their work receive.


Google uses this same principle for websites. When you do a search, there may be millions of pages that have your search terms on them. But you don't want to look at millions, how about the top 10. Google assigns a quality rank to each site it indexes. This quality rank is part of how they get the most relevant results to the top. Again, the quality of a site is partially determined by how often other quality sites refer to it -- just like the scientific article or book.


Check out Part 2 for the economics of how all this Google goodness is free.