
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 |
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