Download Internet Concepts and Ethics

CH/S4CS/Oct. 2000
Internet Concepts and Ethics
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A
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The Internet is a large “network of networks.” It connects tens of thousands of networks, millions of
computers, and many more millions of users in every country.
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The Internet is a worldwide network of computers that has emerged as the enabling technology in our
migration to a global village.
is a communication system that connects two or more computers and their peripheral devices.
Dialup Connection
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The most common form for internet connection is a
. It is a
temporary connection established using a modem to dialup the number for a linked to a remote computer.
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To use this kind of connection, you must have
i.
a computer with a modem,
ii.
a telephone line,
iii.
software(s) for web browsing and E-mail management, and
iv.
an account with an ISP.
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A
is a device used to change the data from the digital form stored in the computer to
the wave form to be transmitted.
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An
(
) is a company that provides individuals and
organizations with access to, or presence on, the Internet.

To start up the dial-up connection, double-click on the dial-up connection icon and enter the necessary on
the corresponding dialogue box.
p. 98 WK Kwok
Web page browsing
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The main purpose of internet access is usually web page browsing. The world wide web (WWW)
contains millions of web pages containing tremendous information from all over the world.
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A
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After you have started up the internet browser, you have two main methods to visit various web page.
is the main web page for a person or organisation.
i.
Each web page has an address or
(
know the address of the page that you want to visit, just type the address to visit.
ii.
Most web pages have hyperlinks to other web pages. To visit these web pages, single-click on the
link.
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).
If you
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The trailing domain of a web address represents the nature of page:
.com
a company or other commercial institution or organisation
.gov
a government site
.mil
A military site
.net
usually, gateways and other administrative hosts for a network
.org
a domain reserved for private organisations that don’t comfortably fit in the other classes
Electronic Mail
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Electronic mail, or e-mail allows us to send and receive from people all over the world.
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Every e-mail address is
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The mailbox part is the name of the mail given by the ISP, and is usually the user identification. The
domain name is the unique name of the e-mail server.
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In addition to mail service provided by the ISP, there is another type of mail called web-based mail. All
you have to do is to register in such web page provided by web index services, e.g. Hotmail, Yahoo.
. It has the format <mailbox>@<fully qualify domain name>.
Search Engine
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New web pages were being added in great numbers every day. The information were in seemingly
random locations, with no easy method of finding pages on a particular subject.
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Search Engine is a web site that runs web index services to make it possible to search for URLs’
addressing.
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These services let you type in one or more words and search their indices for matches of varying
accuracy. A list of links of matching web pages will be displayed.
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Some services also sorted the pages by subject areas and let you search on a particular topic.
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Sample search engine: Yahoo: www.yahoo.com, Infoseek: infoseek.go.com, Lycos: www.lycos.com
Effects of the Internet
i.
Internet users can e-mail other users.
ii.
Internet provides access to million of pages of information with excellent research facilities.
iii.
Users can have internet access from anywhere usually for the price of a local phone call.
iv.
There are dangers of pornography and racist literature. Some ISPs try to ‘firewall’ these pages, that
is not allow access to them.
v.
It is impossible to police.
vi.
Internet shopping may affect traditional shops.
**Something to remind you
1.
There are millions of pages in the world wide web. It is easy to get lost in it. You should have decided
what you want before you log on.
2.
You should never download any illegal copies of software, songs, films, etc.
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Home Page Construction
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Web pages are written in a special kind of language known as Hyper Text Markup Language (HTML).
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Many people have put their Web pages on the Internet to communicate with others. You may use your
Web pages to show off yourself, to help other people, and to help yourself.
** A home page is the first page of a set of Web pages created by a user or an organisation.
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For individual, this introductory page often contains a picture of the page owner, some personal
information that he wants to publish, some links to his Web pages, and some links to other Web pages he
wants people to visit.
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For businesses, a home page usually has a company logo and a short introduction to the company on it.
From that page, people can go to other related pages created by that company. Those pages usually
describe the company background, provide product-related or service-related information.
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Criteria of good Web pages
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i.
Content. Present the content of your pages in a straightforward way. The pages should provide
something of interest or of value to others. The content should be up-to-date and be constantly
updated.
ii.
Clarity. Present your information clearly. Avoid putting too much text on pages for attracting
visitor’s attention. Viewing too much text on a small screen is never comfortable. Remember to
include plenty of blank space and separation in your text. Divide your text into logical blocks which
are put on separate but inter-linked pages.
iii.
Colour. The effect of a good use of colour is very important. E.g. Blue and yellow are the colours
of information and red is the colour for “warning” or “danger”. Some colour combinations do not
work well. Try to avoid combining dark colours like blue with black, green, or red.
General Steps of creating Web pages:
i.
Decide the contents. This involves listing what information you want to convey to readers of your
Web pages and grouping the different kinds of information into categories.
ii.
Design the paths to follow. This involves designing the way to navigate through your pages.
iii.
Design how information is presented. This involves designing how your information is presented.
(In a more formal or funnier way?)
iv.
Implement the page. By writing your page in HTML or using Web developing kit.
Hyper-Text Markup Language (HTML).
i.
A markup language is a pseudo-computer language that combines plain text and formatting features
together.
ii.
HTML is a special markup language for creating hypertext document.
Here is a sample hypertext document (Try browse the page on the LAN server.)
<HTML>
<HEAD>
<TITLE>Sample</TITLE>
</HEAD>
<BODY>
<img src="welcome.JPG" HEIGHT=98 WIDTH=281>
<center><i><font size=6>My Homepage
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</font></i></center>
<HR size=2>
<big><b><FONT COLOR="purple">
Choose what you want to know about me...</big></b></font>
<center><i><small>
<p>Click <A HREF="MyProfile.htm">
My Profile</A> to see a profile of me;
<p>or click <A HREF="MyHome.htm">
My Home</A> to enter my home;
<p>or click <A HREF="MyJob.htm">
My Job</A> to know about my job.
</center></i></small>
<p ALIGN="right"><big><b><i>You may also send me a
<A HREF="mailto:[email protected]">
Mail<img src="mailbox.JPG" HEIGHT=89 WIDTH=79></A>
</font></i></b>
</BODY>
</HTML>
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HTML tags
i.
Each special code is known as an HTML tag that contains an element name enclosed by a pari of ‘<’
and ‘>’. The HTML tags tell Web browsers how to display and print this document.
ii.
Most of the HTML tags occurred in pairs: known as a begin tag and an end tag. Both tags bear the
same element name but the end tag contains a forward slash before the tag name. E.g. <p> and
</p>.
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An HTML document is a plain text file. It must have the extension “.htm” or “.html” in the file name.
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There are two sections - the head section and the body section. They are enclosed by the tags: <head>
and </head>, <body> and </body>.
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The unit of body text can either a heading or a paragraph:
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i.
A heading can be of different levels, from 1 to 22, enclosed by <hn> and </hn> where n is heading
level number. The smaller the level number, the larger the font size it will be.
ii.
A paragraph is enclosed by <p> and </p>. Most browsers align paragraphs of text to the left
margin and wrap the text to the next line if necessary. (</p> is not required.)
There are many tags for text formatting. Here are some example:
<b>…</b>
Use a bold font.
<i>…</i>
Use Italics.
<u>…</u>
Underlined text.
<s>…</s>
Strike-through text.
<big>…</big>
Use larger font size.
<small>…</small>
Use smaller font size.
<var>…</var>
Show a word or words as a variable.
<tt>…</tt>
Use a typewriter font.
<kbd>…</kbd>
Use a typewriter font as input from the keyboard.
<code>…</code>
Use a typewriter font as for source code examples.
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<cite>…</cite>
Show a word or words as citation.
<sample>…</sample> Show a word or words as sample.
<em>…</em>
Show the text with emphasis.
<strong>…</strong>
Use strong emphasis (e.g. bold).
<!--- comment --->
HTML comment, no effect with the general form.
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Font Size and Font colour
You can also set the font size and font colour by the tags <font size=n>…</font> and <font
color=“color”>…</font>. E.g.
i.
<font size=6><font color="purple">
These text will be displayed in purple with font size 6.</font></font>
Here are some commonly used font colours:
ii.
“black”, “red”, “blue”, “green”, “white”, “cyan”, “purple”, “yellow”, “brown”, “dark red”, “dark blue”,
“dark green”, “grass green”, “dark grey”, “dark purple” and “dark yellow”
You can also define font colours using the different combination between the three primary colours
Red, Green and Blue. Each colour is represented the two digit hexadecimal number in order Red,
Green and Blue as follows.
iii.
<font color=#c0dcc0>The text will be displayed in Grass Green.</font>
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Special characters. Some special characters have special meaning in HTML, e.g. ‘<’ and ‘>’. We can
display these special characters as with ampersand sign (&) as follows:
&lt; for ‘<’
&gt; for ‘>’
&amp; for ‘&’
&quot; for ‘"’.
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Lists
i.
Unordered list (bulleted), e.g.
<ul>
<li>F1-3 Computer Literacy
<li>F4-7 Computer Studies
<li>F6-7 Computer Applications
</ul>
It will be displayed as follows:



ii.
F1-3 Computer Literacy
F4-7 Computer Studies
F6-7 Computer Applications
Ordered list, e.g.
<ol>
<li>F1-3 Computer Literacy
<li>F4-7 Computer Studies
<li>F6-7 Computer Applications
</ol>
It will be displayed as follows:
1.
2.
3.
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F1-3 Computer Literacy
F4-7 Computer Studies
F6-7 Computer Applications
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iii.
Definition list, e.g.
<dl>
<dt>F1-3
<dd>Computer Literacy
<dt>F4-7
<dd>Computer Studies
<dt>F6-7
<dd>Computer Applications
</dl>
It will be displayed as follows:
F1-3
Computer Literacy
F4-7
Computer Studies
F6-7
Computer Applications
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Anchors
i.
Anchors are the cross-references that define the hypertext in HTML documents.
ii.
An anchor consists of a pair of tags <a> and </a>, and a number of attributes.
iii.
The href attribute is its most important attribute that defines the object to which the anchor is linked,
e.g.
<a href="http://www.cuhk.edu.hk">Click the text to go to the CUHK Web
page.</a>
<a href="mailto:[email protected]">Click the text to start the mail client
to compose e-mail to Cheng Him.</a>
iv.
You can also set links inside a large web page. First set labels on a page by the name attribute as
follows,
<a name="Main">
Then if you want to navigate back to the position of the above label, just code as follows:
<a href="#Main">Click the text to go back to Main.</a>
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v.
Those text included in the anchor will be displayed as hot-spots by the web browser. (Usually italic,
underlined and blue in colour.)
vi.
Note that you can also create a link to a sound file, thus when you click the hypertext, sound
application would be invoked and the sound effect or music would be played.
Display Images
i.
You can use the image tag <img> to display an image in your Web page. The source of the image is
specified with the src attribute. e.g.
<img src="trees.gif">
ii.
Newer versions of HTML enable you to specify an alternative image file for browsers to use for rule
lines. e.g.
<hr src="waves.gif">
iii.
You can use the background attribute of the body tag <body> to specify an image file. Browsers
will replicate the image to create a custom background for your Web page. e.g.
<body background="linen.gif" >
iv.
wA hypertext document enables you to format information in a friendly, first thing to do is to define
the data range, i.e. the range of worksheet data to include in the chart. Then you can start to create
the graph by clicking the Chart Wizard button on the Standard toolbar.
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Web Page Development Tools
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A Web page development tool is a program releasing the burden of the users to write HTML codes in
creating Web pages.
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It usually let the users create the Web pages using tools as if they are using a word processor to make
ordinary documents. Throughout the process, suitable HTML tags are inserted into the documents by the
program.
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There are plenty of Web page development tools available in the market. Some of them are even free to
download from the Internet.
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You can also develop Web page by Word 97 or PowerPoint 97.
Proxy Server
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A Proxy Server is a server provided by the ISP. A group of internet users may share the usage of a proxy
server.
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The server can access the internet faster than your personal computer. Thus you can choose to access
internet via a proxy server. Documents which have been accessed by the users in the group may be
stored in the proxy server in a period. If you want to access these documents in the server, it will be
much faster.
Plug-in

You can add some plug-in application to your web page browser. E. g. Real player, Shockwave.

These plug-ins may help you a lot in viewing audio / video information from the web page. If you access
web page with audio / video information, the plug-in application will be automatically executed and play
the music or video.
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