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What are the differences between the various search engines?
Subject Directory
engines depend on individuals registering their web pages with a
company such as Yahoo. These search engines are ordered in nature,
classifying registered web pages by subject, thus providing a type
of directory or index to websites.
Active Search engines make use of a computer program (a "spider")
that travels out along the Web searching for sites. When the program
reaches a web page, it actually explores all the links at that site
and indexes them. When you use one of these search engines, you
are not actually searching the entire Web, but rather the engine
is searching its own index.
Meta-search engines don't assemble their own index of websites,
but search the indices of subject directory and active search engines,
and then provide a summary of results from each search engine. This
type of search engine is not very useful for queries which bring
in a large number of responses, but can be a useful shortcut for
simple searches involving unique keywords or phrases.
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