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Power Googling: How Google Works

Google consists of three distinct parts

Googlebot, Google's web Crawler

Googlebot finds and retrieves pages on the web in two ways:

Screen shot of web page for adding a URL to Google.

Google rejects URLs that it suspects are trying to deceive users by employing tactics such as

Google crawls deeply by harvesting links from every page it encounters.

To keep the index current or fresh, Google continuously recrawls popular frequently changing web pages.

The combination of the two types of crawls (deep and fresh) allows Google to

Google's Indexer

Googlebot gives the indexer the full text of the pages it finds.

To improve search performance,

For rapid access to documents that contain user query terms, the index is sorted alphabetically by search term, with each index entry storing

Google's Query Processor

The query processor includes

Google considers over a hundred factors in determining which documents are most relevant to a query, including

Google also applies machine-learning techniques to improve its performance automatically by learning relationships and associations within the stored data, e.g., the spelling-correcting system.

A patent application discusses other factors that Google considers when ranking a page. Visit SEOmoz.org's report for an interpretation of the concepts and the practical applications contained in Google's patent application.

Since Google indexes HTML code in addition to the text on the page, users can restrict searches on the basis of where query words appear, e.g.,

Let's see how Google processes a query.

A graphic of a user's computer.
3. The search results are returned to the user in a fraction of a second.     1. The web server sends the query to the index servers. The content inside the index servers is similar to the index in the back of a book--it tells which pages contain the words that match any particular query term.
2. The query travels to the doc servers, which actually retrieve the stored documents. Snippets are generated to describe each search result.
Copyright © 2003 Google Inc. Used with permission.

For more information on how Google works,

This page was last modified on Monday February 27, 2006.


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