This document describes how search engines work by having spiders find and read web pages to build an index of words and links within each page. The index then allows the search engine to query for specific terms, rank results by relevance, and return relevant pages that contain the searched words and have more incoming links.

1. How Do Search Engines Work ? Page A This page is red & square Page B This page is blue & square Search Engine Index Page Color Shape Links A Red Square 7 B Blue Square 3 Page C This page is green & oval search for “red” returns ==  A search for “square” returns ==  B,A search for “oval” returns ==  SPIDER - finds & reads pages INDEX - inventories words & links SEARCH - queries index, ranks & returns results