Transcript What is the Internet? - University of Pretoria

What is the Internet?
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It is the world-wide distributed network of
computers connected using TCP/IP
(Transmission Control Protocol/Internet
Protocol) : the protocol used to transmit data
across the networks
 IP: packages and addresses the data
 TCP: breaks data up into packets : verifies
that all packets arrive at their destination and
“reassembles” the data
What is the Internet

It has no central control - works through the
cooperation of network administrators
 It was created by the US Department of
Defence to carry information to defence
contractors
 South Africa linked to Internet since April
1989 via research network called Uninet to
link all university, educational and research
institutions in country
Benefits of using Internet
Communication locally / internationally
faster and more cost effective
 Long distance telephone charges
eliminated by using e-mail
 Creates better informed staff/students
with access to resources not otherwise
available
 Good for advertising services / facilities
offered by institutions/companies
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Internet Facilities
FTP (File Transfer Protocol): a
mechanism for transferring files across
a network
 BULLETIN BOARD: the Internet
equivalent of a notice board, where
messages can be posted and read by
anyone
 NEWSGROUP: a discussion group
distributed via USENET in which users
leave messages for others to read
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Internet Facilities
(cont)
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TELNET: a program that allows users to login
to distant computers via TCP/IP and usually
needs a password
 LIST SERVERS: a program that sends
mailing lists to subscribers by e-mail
 E-MAIL: a means of exchanging messages
and files from one computer to another. EMail address e.g.
– [email protected]
World Wide Web (WWW)
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Hypertext access to information on the
Internet - links documents known as web
pages
 Creates documents in HTML (Hypertext
Mark-up Language)
 Special browsers needed to read documents
e.g. Netscape or Internet Explorer
 Every document has it’s own address or URL
(Universal Resource Locator) - case sensitive
Bookmarks / Favourites

Bookmark your favourite URL’s for
direct access with only a click
Netiquette
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No insulting messages
Do not send anything that you do not want to be
known
Be polite - use smiley’s :-) ;-) :-| :-(
Do not send huge signatures
Network is for academic purposes = work and
research
See http://www.albion.com/netiquette/
Search Engines
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Search engines help you to sort through the
masses of information on the WEB
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Major search engines are: Fast, Alta Vista,
Google, Yahoo, Lycos, HotBot, Excite,
Magellan, Infoseek
Which search engine is the
biggest / best?
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Search engines are constantly evolving :
competition is fierce
 Some handle boolean queries better e.g.
Northern Light and Alta Vista
 Some better on relevance ranking e.g.
Google
 Some more user friendly e.g. Ask Jeeves but results not as good as larger search
engines
Which search engine is
biggest / best?
Search engine database sizes in
constant flux. Three largest are those
of the Inktomi group, Northern Light and
Fast
 Greg Notess site http://www.notess.com
give regular updates on search engine
sizes
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How do search engines work?
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There are four main functional parts:
– Engine’s “spiders” (also known as
“crawlers”) go and find web sites/pages
– Indexing program indexes sites
found/submitted
– Retrieval engine : retrieves information
from index on receipt of query
– Graphical interface : gathers query data
from user to feed to retrieval engine
Comparing search engines
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Very few standards in place
Each search engine has own way of dealing with:
– Boolean logic
– Truncation
– Phrase searching
– Case sensitivity
– Sorting by: date, site, categories, etc
– Use HELP files
Evaluation of Internet
resources
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Quality
 Presentation
 Cost and Copyright
 Hardware and Software
Evaluation of Internet
resources
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Quality:
– Who is the audience?
– What is the purpose of the Web Page / what does it
contain
– How complete and accurate are the information / links
provided
– Are the links relevant and appropriate for the site?
– Are the links comprehensive or just provide a sampler?
Quality (cont)
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How up-to-date are the links?
Is the resource full text?
Is the Internet version of resource current, e.g. dictionaries
How comprehensive is this site?
Is the resource available from or pointed to by multiple
Internet sites?
Who is the author or producer?
Was content developed by an academic
institution/commercial enterprise with established
reputation?
Quality (cont)
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Does resource stay current through regular updates or
demonstrate on-going maintenance
Was the content peer-reviewed by experts in field?
What are dates of coverage ?
Is any sort of bias evident?
When was the Web item produced?
When was the Web item last revised?
Is contact information for author/producer included?
Evaluation of Internet resources
 Presentation
– Do the graphics /art serve a function or just
decorative?
– Do the icons clearly represent what is
intended?
– Does the text follow basic rules of
grammar, spelling and composition?
– When is it necessary to send confidential
information : How secure is it?
Evaluation of Internet
resources
 Cost and Copyright
– Are subscription or access costs involved?
– What security is provided for payment?
– What copyright regulations are applied?
Evaluation of Internet
resources
 Hardware
and Software
– Is sound equipment or additional software
required for full access to a resource.
Conclusion
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The Internet is a rich source of information,
which can be used to great advantage.
However, because there is no control over
the material that is placed on the Internet,
evaluate any information very carefully.
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Main method of retrieving information these
days is from computerized databases. e.g.
Medline