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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:
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
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.
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,
- Google's page on Google's Technology, www.google.com/technology/
- How does Google collect and rank results?, www.google.com/newsletter/librarian/librarian_2005_12/article1.html
- Google's Pagerank Algorithm and How it Works, www.iprcom.com/papers/pagerank/
- Google's PageRank Explained and How to Make the Most of It,
This page was last modified on Monday February 27, 2006.
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For Google tips, tricks, & how Google works, visit
Google Guide at www.GoogleGuide.com.|
By Nancy Blachman and Jerry Peek who aren't Google employees. For permission to copy
& create derivative works, visit Google Guide's Creative Commons License webpage.