Introduction To Searching

How Do Search Engines Work?

• Search engines compile their databases by employing "spiders" or "robots" (bots) to crawl through web space from link to link, identifying pages. Sites with no links to other pages may be missed by spiders.
• It is important to remember that when you are using a search engine, you are NOT searching the entire web as it exists at this moment. You are actually searching a portion of the web, that had been captured in a fixed index created at an earlier date.

What are Library Gateways?

• Library gateways are collections of reviewed and recommended links that have been created by subject specialists, usually librarians, to support research needs and to pinpoint high quality sites on the web.
• There is a large portion of the web that search engine spiders cannot index. This portion of the web has been called the "Invisible Web."
• The "Invisible Web" is made up of thousands of databases, many of them maintained by academic institutions, numerous government agencies and business-related databases.
• Library gateways are good sources for direct links to database information stored in the "Invisible Web."
• Examples of Library Gateways: AlphaSearch (http://www.calvin.edu/library/searreso/internet/as/), Argus Clearinghouse (http://www.clearinghouse.net), Infomine (http://infomine.ucr.edu), and Librarians' Index to the Internet (http://lii.org).

What Does the Web Address Mean?

• Example: The MRC's address: http://www.siumed.edu/mrc
  

  http	-protocol
  www	-host computer name
  siumed	-second-level domain name
  edu	-top-level domain name
  mrc	-directory name

  
  
• Only a few top-level domains are currently recognized, but there are changes being made. Here is a list of the domains generally accepted by all:
  

  edu	-educational site
  com	-commercial business site
  gov	-U.S. governmental/non-military site
  mil	-U.S. military sites and agencies
  net	-networks, internet service providers, organizations
  org	-U.S. non-profit organizations and others