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An index entry in a database that
identifies a document or record. Keyword searches form the basis of the
operating of
search engines such as altavista, which search web pages for
unique words and index them accordingly. The simplicity of this approach
belies the difficulty of obtaining useful results from databases of several
million documents, and most search engines use additional criteria to
determine the relevance of a particular keyword's occurrence.
Some
search engines have attracted controversy by selling keywords to advertisers
and ranking searches for these words preferentially. Many others associate
keywords with particular advertisements, so that a search for "computer"
will display a computer vendor's banner at the top of the search results
page. pornography sites have taken particular advantage of this
feature, to the displeasure of many web users confronted with graphic
advertisements following innocent searches , especially for words describing
parts of the body. |
