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How Internet Search Engines Work


Building a Search

Searching through an index involves a user building a query and submitting it through the search engine. The query can be quite simple, a single word at minimum. Building a more complex query requires the use of Boolean operators that allow you to refine and extend the terms of the search.

The Boolean operators most often seen are:

  • AND - All the terms joined by "AND" must appear in the pages or documents. Some search engines substitute the operator "+" for the word AND.
  • OR - At least one of the terms joined by "OR" must appear in the pages or documents.
  • NOT - The term or terms following "NOT" must not appear in the pages or documents. Some search engines substitute the operator "-" for the word NOT.
  • FOLLOWED BY - One of the terms must be directly followed by the other.
  • NEAR - One of the terms must be within a specified number of words of the other.
  • Quotation Marks - The words between the quotation marks are treated as a phrase, and that phrase must be found within the document or file.