3.4. HOW SEARCH WORKS
Google rocks. It raises my perceived IQ by at least 20 points. I can pull a reference or quote in seconds, and I can figure out who I'm talking to and what they're known for—a key feature for those of us who are name-memory challenged.
—Wes Boyd, president, MoveOn.org
Google once claimed that pigeons powered its search results, but that was just another April Fool's Day joke.
It is estimated that in 2007 Google was processing more than 37 billion searches per month, compared with 8.5 billion by Yahoo! and 2.2 billion by Microsoft. Most people search out information on the Internet, often multiple times each day. Yet few people comprehend how search really works.
In simplified form, it goes something like this:
You enter a word or series of words, and the search engine connects you to those words in a database it has created. From the outset, Larry and Sergey aimed at putting the entire Internet into its database. The company still strives to do that, plus adding many other sources of information.
The engine searches, using three major segments:
The crawl, which actually doesn't crawl. Rather, it broadcasts requests to thousands of Web pages seeking your search words. The crawler also is called a spider.
The index, a massive database where the words are stored and found.
The runtime system—also called a query processor. This step delivers search results back to the questioner.
This scenario, however, doesn't explain exactly how Google's ...