Some Popular Portals

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Some Popular Portals

• Yahoo! www.yahoo.com
• Portals to the World from the Library of
  Congress www.loc.gov/rr/international/portals.htm
  l
• AltaVista www.altavista.com

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Search Engines?

• A search engine is a web site that uses software
  to browse the Internet.
• A search engine will retrieve a listing of World
  Wide Web sites related to the key words you
  specify.

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How Search Engines Work

• Read pages they find on the web (spider)
• Store text in an index
• When you search, they look for pages with
  matching text
• Other factors involved in ranking those pages,
  such as link popularity

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Search Engine INdexing

• Computer-driven search tool
• Website owners submit web address of their
  homepage for inclusion in the database
• Robots periodically spider the Web, detect the
  homepage and proceed to scan every page in the
  entire website
• (The first 20-25 words on the homepage appear as
  the result the user sees in the search engine)

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Search Engines

• Crawler-based Search Engines
• Spiders or Crawlers visit websites and some
  of their pages periodically, and adds to index
• Scans links and adds them to their index
• Returns the information to the index or catalog
• Search engine software sifts the index and ranks
  in relevant order
• Human-based Search Engines
• Mixed

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Directories Vs Search Engines

• When should you use a directory?
• When you have a broad topic
• When you want experts to recommend sites
• When you want to avoid irrelevant sites
• Examples topics
• Disabilities
• Civil War
• Welfare

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Directories Vs Search Engines

• When should you use a search engine?
• When you have a narrow topic
• When you are looking for a specific website
• When you want to search for a file type or
  language
• Examples
• Americans with Disabilities Act
• Battle of Gettsyburg
• Welfare to Work

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Start Your Search Engines Here

• Google www.google.com
• AllTheWeb www.alltheweb.com
• Yahoo www.yahoo.com
• MSN http//search.msn.com
• Why? See http//searchenginewatch.com/links/majo
  r.html

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Other Search Engine Types

• News Search Engines
• Multimedia Search Engines
• Metacrawlers
• Kids Search Engines
• Regional Search Engines
• Scientific Search Engines http//searchenginewatch
  .com/links/

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Top Search Engines Directories

• Google
• Yahoo!
• AllTheWeb
• AltaVista
• Open Directory
• MSN Search
• About

• Ask Jeeves
• WiseNut
• HotBot
• LookSmart
• Teoma
• AOL Search
• iLOR

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Google

• Google is the undisputed leader in search
  engines, with the largest database and highly
  relevant results
• Uses an algorithm based on site popularity
• The more inbound links pointing to a particular
  site from another site Google thinks is
  worthwhile, then that site will receive a higher
  page rank in the results
• Wary of minimising advertising - no frills
  design, nice clean look and no pop-up ads

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AllTheWeb AltaVista

• AllTheWeb used to be a Norwegian search engine
  FAST and for a while was one of the Webs best
  kept secrets
• AltaVista was the first search engine in 1995 and
  was THE search engine before Google existed
• Recently, Overture acquired FAST and AltaVista
• This year, Yahoo! acquired Overture and Inktomi,
  making Yahoo! the largest network of major search
  tools on the Internet
• AllTheWeb AltaVistas future are now unknown,
  as many results are simply retrieved from Yahoo

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Open Directory Ask Jeeves

• Open Directory Project is the largest
  humanly-compiled search directory on the Web
• As each website is considered for inclusion by a
  human (many dont make it) - quality is assured
• Ask Jeeves uses special natural language
  technology, so the user can ask a complete
  question instead of inputting only a few words
• It then searches its own database and supplements
  this with results from Teoma
• Ask Jeeves is popular with young Web users

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Understand Limitations of Search Engines

• Search spiders or crawlers do not crawl in
  real time
• Lag times getting info to the index vary by
  search engine
• If a website is not submitted to the search
  engine it wont be crawled
• Not every page from a website is crawled
• A webmaster can choose to not have a page crawled
• Formats like PDF, Flash, Zip files, executable
  programs, and others cannot be searched
• The Invisible Web

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Evaluating Web Sites Continued

• Can you find this news reported on a legitimate
  news website?
• Who is the sponsor of the website?
• Are there inconsistencies or inaccuracies in the
  information?
• If an organization is mentioned by name, does the
  organization have any related information on this
  website?

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Meta Search Engine

• Searches more than one search engine
  simultaneously (often up to fifteen)
• Each meta search engine normally searches a
  different combination of search engines
• Simultaneous multiple engine searching saves the
  user lots of time
• But meta search engines only skim the surface of
  each engines database and sometimes lack depth
  when searching for results

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Top Meta Search Engines

• Kartoo
• Turbo 10
• Dogpile
• Mamma
• Red Hot Chilli
• Meta Eureka
• Web Taxi

• Vivisimo
• ixquick
• iBoogie
• Metacrawler
• Supercrawler
• Search.com
• Query Server

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Kartoo Turbo10

• These search tools cluster sets of results on
  similar topics and display them on the side frame
• Kartoo is arguably the funkiest search facility
  on the Web, displaying results as a visual mind
  map
• Theres a basic and expert version for searching
• Turbo10 is unique because it has a long list of
  specialist databases on specific subjects
• Searches the Deep Net (others rarely go there)
• Users can also tailor their searching by
  selecting unusual databases of their own choosing

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Vivisimo, Dogpile Mamma

• Vivisimo also uses clustering technology and
  allows users to choose their own search engines
• Dogpile was one of the earliest meta search
  engines and remains very popular today
• Its major advantage lies in its search engines
  Google, Yahoo!, Ask Jeeves, Teoma, About etc.
• Canadian-based Mamma began in 1996 as a Masters
  thesis, arguably the first meta search
• Today it is a well respected search tool and like
  Dogpile, searches the Webs top engines such as
  Google, Open Directory, Teoma and others

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Image ( Meta) Searching

• Although pictures on websites often appear neatly
  embedded amongst text, each image needs a unique
  URL, allowing picture searching
• Googles image search is one of the best on the
  Web, partly because of the size of its database
• There are also excellent picture meta search
  engines iBoogie, Dogpile, ixquick and 1Banana
• picsearch is solely a picture search engine and
  markets itself as family and user friendly

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Language Translation

• Google and AltaVista offer language translation
• Google will allow you to translate a foreign
  language website or page and even allow you to
  link to the translated page from another website
• AltaVista uses Babel Fish for its translation and
  you can also translate blocks of text
• Some of the best websites on Bertolt Brecht and
  his Epic Theatre are actually in German, so this
  is an example of where translation tools are
  worthwhile if you speak another language

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Useful Reference Tools

• You can find free dictionaries online, such as
  Merriam Webster, Oxford, Macquarie, Cambridge and
  Dictionary.com
• Most dictionaries also have a thesaurus tab
• The meta dictionary OneLook simultaneously
  searches nearly 1,000 generalist and specialist
  dictionaries!
• Some of the weirdest words out there are at the
  Strange and Unusual Dictionaries website
• Or visit RyhmeZones Rhyming Dictionary
  Thesaurus for a bit of fun!

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More Reference Tools

• If looking for the origin of a phrase or saying,
  try Brewers Dictionary of Phrase and Fable
• Theres also the ClichéSite or the Hutchinson
  Dictionary of Difficult Words
• Free encyclopaedias include Encyclopedia.com,
  Columbia, Encarta (partly free), Wikipedia,
  Hutchinson the 1911 Encyclopaedia Britannica
  considered by many to be the best edition ever!
• Way Back Machine has been archiving large
  portions of the Web since 1996, so if a website
  has suddenly disappeared, search for it here!

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The Invisible Web

• Web information that does not get indexed by the
  major search engines.
• Hidden mostly in databases or have robot.txt file
  attached
• Data created on the fly from the backend
  (cgi-bin, etc)
• More than ¾ of information on the Web is part of
  the IW.

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The Invisible Web 4 Types

• Opaque search engines choose not to index
• The Private Web password protected
• The Proprietary Web registration required
  (either fee or free)
• The Truly Invisible Web cant search certain
  file formats and databases

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Examples of the IW

• Online telephone and address databases
• News engines
• Professional look-up services (AMA)
• Movie and Book Reviews
• Education databases (ERIC)
• Medical databases (Medline)