INTRODUCTION TO THE INTERNET AND WEB
Internet
•
It is the largest
network in the world that connects hundreds of thousands of individual networks
all over the world.
•
The popular term for
the Internet is the “information highway”.
•
Rather than moving
through geographical space, it moves your ideas and information through
cyberspace – the space of electronic movement of ideas and information.
•
No one owns it
•
It has no formal
management organization.
•
As it was originally
developed by the Department of defense, this lack of centralization made it
less vulnerable to wartime or terrorist attacks.
•
To access the
Internet, an existing network need to pay a small registration fee and agree to
certain standards based on the TCP/IP (Transmission Control Protocol/Internet Protocol)
.
The uses of the Internet
•
Send e-mail messages.
•
Send (upload) or
receive (down load) files between computers.
•
Participate in
discussion groups, such as mailing lists and newsgroups.
•
Surfing the web.
What is Web?
•
The Web (World Wide
Web) consists of information organized into Web pages containing text and
graphic images.
•
It contains hypertext
links, or highlighted keywords and images that lead to related information.
•
A collection of linked
Web pages that has a common theme or focus is called a Web site.
•
The main page that all
of the pages on a particular Web site are organized around and link back to is
called the site’s home page.
How to access the Internet?
•
Many schools and
businesses have direct access to the Internet using special high-speed communication
lines and equipment.
•
Students and employees
can access through the organization’s local area networks (LAN) or through
their own personal computers.
•
Another way to access
the Internet is through Internet Service Provider (ISP).
•
To access the Internet,
an existing network need to pay a small registration fee and agree to certain
standards based on the TCP/IP (Transmission Control Protocol/Internet Protocol)
reference model.
•
Each organization pays
for its own networks and its own telephone bills, but those costs usually exist
independent of the internet.
•
The regional Internet
companies route and forward all traffic, and the cost is still only that of a
local telephone call.
Internet Service Provider
(ISP)
•
A commercial
organization with permanent connection to the Internet that sells temporary
connections to subscribers.
•
Examples:
•
ZANLINK, Simbanet,
ZANTEL, TTCL America Online, Microsoft network, AT&T Networks. etc
How to access the Web?
•
Once you have your
Internet connection, then you need special software called a browser to access
the Web.
•
Web browsers are used
to connect you to remote computers, open and transfer files, display text and
images.
•
Web browsers are
specialized programs.
•
Examples of Web
browser: Mozzila, Netscape Navigator (Navigator), Google chrome and Internet
Explorer.
Client/Server Structure of
the Web
•
Web is a collection of
files that reside on computers, called Web servers that are located all
over the world and are connected to each other through the Internet.
•
When you use your
Internet connection to become part of the Web, your computer becomes a Web
client in a worldwide client/server network.
•
A Web browser
is the software that you run on your computer to make it work as a web client.
Hypertext Markup Language
(HTML)
•
The public files on
the web servers are ordinary text files, much like the files used by
word-processing software.
•
To allow Web browser
software to read them, the text must be formatted according to a generally
accepted standard.
•
The standard used on
the web is Hypertext markup language (HTML).
•
HTML uses codes, or
tags, to tell the Web browser software how to display the text contained in the
document.
•
For example, a Web
browser reading the following line of text:
<B>
A Review of the Book<I>Wind Instruments of the 18th
Century</I></B>
•
recognizes the
<B> and </B> tags as instructions to display the entire line of
text in bold and the <I> and </I> tags as instructions to display
the text enclosed by those tags in italics.
Addresses on the Web:IP
Addressing
•
Each computer on the
internet does have a unique identification number, called an IP (Internet
Protocol) address.
•
The IP addressing
system currently in use on the Internet uses a four-part number.
•
Each part of the
address is a number ranging from 0 to 255, and each part is separated from the
previous part by period,
•
For example,
106.29.242.17
Domain Name Addressing
•
Most web browsers do
not use the IP address t locate Web sites and individual pages.
•
They use domain name
addressing.
•
A domain name
is a unique name associated with a specific IP address by a program that runs
on an Internet host computer.
•
This program, which
coordinates the IP addresses and domain names for all computers attached to it,
is called DNS (Domain Name System ) software.
•
The host computer that
runs this software is called a domain name server.
•
Domain names can
include any number of parts separated by periods, however most domain names
currently in use have only three or four parts.
•
Domain names follow
hierarchical model that you can follow from top to bottom if you read the name
from the right to the left.
•
For example, the
domain name gsb.uchicago.edu is the computer connected to the Internet at the
Graduate School of Business (gsb), which is an academic unit of the University
of Chicago (uchicago), which is an educational institution (edu).
•
No other computer on
the Internet has the same domain name.
Uniform Resource Locators
•
The IP address and the
domain name each identify a particular computer on the Internet.
•
However, they do not
indicate where a Web page’s HTML document resides on that computer.
•
To identify a Web
pages exact location, Web browsers rely on Uniform Resource Locator (URL).
•
URL is a four-part addressing scheme that tells
the Web browser:
Ø
What transfer protocol
to use for transporting the file
Ø
The domain name of the
computer on which the file resides
Ø
The pathname of the
folder or directory on the computer on which the file resides
Ø
The name of the file
Structure of Uniform
Resource Locators
http => Hypertext Transfer
Protocol
HTTP
•
The transfer protocol
is the set of rules that the computers use to move files from one computer to
another on the Internet.
•
The most common
transfer protocol used on the Internet is the Hypertext Transfer Protocol
(HTTP).
•
Two other protocols
that you can use on the Internet are the File Transfer Protocol (FTP) and the
Telnet Protocol
How to find information on the Web?
•
A number of search
tools have been developed and available to you on certain Web sites that
provide search services to help you find information.
•
Examples:
Ø
Yahoo à
www.yahoo.com
Ø
Excite à
www.excite.com
Ø
Lycos à
www.lycos.com
Ø
AltaVista à
www/alta-vista.com
Ø
MSN WebSearch à
www.search.msn.com
How to find information on
the Web?
•
You can find
information by two basic means.
•
Search by Topic and Search by keywords.
•
Some search services
offer both methods, others only one.
•
Yahoo offers both.
Ø
Search by Topic
You
can navigate through topic lists
Ø
Search by keywords
You
can navigate by entering a keyword or phase into a search text box.
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