文档介绍：How Search Engines Work
by Curt Franklin
The good news about the and its most ponent, the World Wide Web, is that
there are hundreds of millions of pages available, waiting to present information on an amazing
variety of topics. The bad news about the is that there are hundreds of millions of pages
available, most of them titled according to the whim of their author, almost all of them sitting on
servers with cryptic names. When you need to know about a particular subject, how do you know
which pages to read? If you're like most people, you visit an search engine.
search engines are special sites on the Web that are designed to help people find
information stored on other sites. There are differences in the ways various search engines work,
but they all perform three basic tasks:
• They search the -- or select pieces of the -- based on important words.
• They keep an index of the words they find, and where they find them.
• They allow users to look for words binations of words found in that index.
Early search engines held an index of a few hundred thousand pages and documents, and
received maybe one or two thousand inquiries each day. Today, a top search engine will index
hundreds of millions of pages, and respond to tens of millions of queries per day. In this edition of
HowStuffWorks, we'll tell you how these major tasks are perform