How search engines work????

What follows is a basic explanation of how search engines work.  For more detailed and technical information about current methods used by search engines like Google, check out our discussion of Search Engine Ranking Algorithms

    * Keyword Searching
    * Refining Your Search
    * Relevancy Ranking
    * Meta Tags
    * Concept-based Searching (This information is dated, but might have historical interest for researchers)

Search engines use automated software programs knows as spiders or bots to survey the Web and build their databases. Web documents are retrieved by these programs and analyzed.  Data collected from each web page are then added to the search engine index.  When you enter a query at a search engine site, your input is checked against the search engine's index of all the web pages it has analyzed.  The best urls are then returned to you as hits, ranked in order with the best results at the top.