Major Search Engines On the Web
  • In 1994, there were 20 million pages- In 2004, there were 8 billion
  • Search engines "crawl" sites
    • Revisit them every month
    • Will only look at first 100-500 K of information
  • Ranking- How high up on results list a site appears based on:
    • Amount of information on site
    • Amount of other sites that link to it
    • Amount of people that select that link when searching
    • Length of time site has been listed in search engine database
    • Code of the site
    • Sponsored Links
      • Payed for by advertisers
      • Not relevant to your search
  • Google- Largest
  • MSN & Yahoo- 2nd and 3rd Largest
  • Lycos- Searches by region, language and date
  • Altavista- Searches images, audio, video and news
  • Ask Jeeves- Formulates search based on the question you ask
  • Bing- Microsoft's search engine
  • The Open Directory Project- Allows only higher quality websites

MetaSearch Engines
  • Searches other search engines
  • Only basic searches
  • Searches pay-per-click advertisers, so some searches are weak on validity
  • Dogpile, Mamma, Metacrawler

Invisible Web