The Internet
What
is the Internet?
The Internet is a communications
network linking computers worldwide. It forms the nervous system of the
World Wide Web (WWW)
At the center of the Internet is a
high speed “backbone” which carries data around the world. Telephone
company landlines, ISDN lines, and other high-speed data connections
link literally millions of homes and businesses to this backbone itself.
You may also hear gateway computers referred to as Hosts,
or servers. Your computer is referred to as a Client.
However, the average computer user cannot link directly
to the backbone. Instead, we connect to the Internet using a computer
dedicated solely to maintaining an Internet connection, or Gateway.
You can find a detailed history of the Internet from the
sites
http://www.isoc.org/internet-history/
How do I Connect to the Internet?
There are a number of different ways to connect to a Internet:
Establish
your own:
Set up your own computer and domain name with a registrar authorised by
Internic (http://www.internic.net/).
Internic is the organization that controls registration of Internet
domain names. Examples for registrars are Network
Solutions (http://www.networksolutions.com)
and Reigster.com (http://www.register.com)
Connect
through an on-line service:
Most of the large on-line services, such as CompuServe, America Online,
and MSN have their own gateways, which you can use to connect to the
Internet. This is a relatively simple, user-friendly way to access the
Internet. However, the large volume of users on these services can slow
down access.
Connect through an Internet Service
Provider:
An Internet Service Provider (ISP) provides you with direct dial-up
access to their gateway. This allows you the closest thing to direct
Internet access without owning your own gateway. This can offer you the
most reliable Internet connection, but you must be careful that you
select a quality ISP.
Unlike countries like India, UK,
USA, there is only one ISP in Oman - Omantel (http://www.omantel.net.om)
How do
I Get Information from the Internet?
There are several different types of services available
to you on the Internet:
Communication Services:
These services include e-mail and Tel-net. This is the
simplest information access method: You connect to the Internet, and
send and receive files directly from other computers.
Information Search Services:
These services allow you to search databases of
information, plus learn of other Internet services which may have the
information you need. These services include Gopher, WAIS and Archie
File Transfer Protocol (FTP):
This service allows you to transfer files from one
location on the Internet to another.
The World Wide Web (WWW):
The World Wide Web is a graphical interface to
information accessible on the Internet. You can access the WWW using any
standard Web Browser
The World Wide Web
What is the WWW?
The WWW is not actually a single entity.
Rather, it is a client-server network that includes web servers, which
are designed to deliver files that are written in HyperText Markup
Language, or HTML, to your computer, which is the client. These
computers use the Internet to connect to each other.
How do I connect to the WWW?
If you have a connection to the Internet,
you can access the WWW using any web browser, such as Internet Explorer
or Netscape. Web browsers interpret the HTML files stored on the web
servers and display the result on your computer screen. All you need to
know is the address of the HTML files you wish to view.
How
do I find something on the WWW?
To locate an HTML file on the WWW, you
need to know its Uniform Resource Locator (URL). The URL
is the ‘user-friendly’ representation of a file’s address on the
Internet. So, a website might have an IP address of 199.222.333 — this
is not easy to remember. However, the URL for that address might be
http://www.microsoft.com
To download an HTML file for which you know the
URL, do the following:
1.
Start your web browser.
2.
Type
the URL in the Location, Go To or Address field of the browser window,
and press Enter.
The name of the field may differ from
browser to browser. However, it is always at the top of the web browser
window.
If You Do Not Have the URL
If
you do not know the URL for the file you want, you can use any one of
the many search engines on the WWW.
These
are the URLs for some of the more popular search engines:
http://www.yahoo.com
Is
the easiest search engine to use, and has a tremendous amount of
content.
http://www.lycos.com
Probably has the best keyword search capability on the WWW.
http://infoseek.com
The URL
Naming Convention
The URL concept is a naming system used to
guarantee that all files stored on the Internet use a common set of tags
to show their location. URLs contain location data for a particular
file: service://host/path/file.ext
Service
Indicates what Internet protocol you will use to access the document.
Common services include the following:
Service |
Description |
ftp:// |
Download a file using FTP |
http:// |
Download an HTML file using HyperText Transfer Protocol |
telnet:// |
Access a remote computer using telnet. |
Host
Indicates the machine from which you are downloading the file. Your host
could be
www.microsoft.com.
Path
Indicates where the file is located on the host. So, if you are
downloading a file located in the “windows” directory on
www.microsoft.com, then you would use the URL
www.microsoft.com/windows/
file.ext
Is the name of the file you are downloading. So, if you were downloading
an HTML file called “page1.html”, located in the docs directory on
www.mysite.com
you would use the following URL:
http://www.mysite.com/docs/page1.html
How does it work?
Exactly how your computer finds, retrieves and
sends information to the WWW is outside the scope of this handout. For
the purposes of this handout, however, one can break the process into
five steps:
1. You enter the URL for a
particular file into your web browser, or click
on a link that connects to the file
2. The browser sends a request to the WWW for
that file.
3. Your request is routed to the correct web
server.
4. The web server delivers the file to the web
browser on your PC.
5. Your web browser interprets the HTML coding
in the file and displays the result on your screen.
How your web browser actually finds the specific
file requested in the millions of files on the WWW could be an entire
book of its own, and is not covered here.
What is a
Web Site?
A web site is simply a collection of files, linked
together and stored on a web server. These files are text files, coded
in the HTML language. Files are stored on a web server just as they are
stored on a PC. They are saved in a directory or set of directories.
There are many different terms used to define
different components of a web site. Sometimes the entire web site is
referred to as a web page, or home page. To avoid adding confusion to
this subject, we will use the following terms throughout this
Website:
Web
Site
The completed collection of files installed on a web server.
Page
A single file or document in a web site.
Home
Page:
The first page a web browser sees when it connects to a site.
Hypertext
Markup Language
Linear Media
Linear media describes with a defined
beginning and a linear progression to the end. Forms of linear media
such as films, audio and videotape, as well as most books are organised
with this expectations. The World Wide Web (WWW), however, is organised
differently.
Hypermedia
Hypermedia is about choice. Users
simply select what interests them. A good example is an audio CD where
you can choice song 4 and listen to it almost immediately. Contrast this
with an audiotape where you would have to scan through from your current
location on the tape to the beginning of the song.
When this concept is applied to text, you will get
hypertext, where by clicking on a link or hotspot (hyper link) you are
transported to a new location within the same page or to a new page
altogether..
When you interlink a large number of pages of text
on different computers all over world, you get a spider web-like system
of all links and pages. This is know as World Wide Web – system whereby
pages stored on many different web servers, connected to the internet,
are linked together.
What is
Hypertext Markup Language?
The WWW connects a tremendous number and
variety of computers: Macintoshes, PCs, UNIX terminals and other
computers all share information on the Web. All of the users of these
computers want to see graphically rich content, including photographs,
formatted text, and tables. Somehow, all of these computers need to have
a common language — a single piece of information should look nearly
identical on all of the different platforms, even if it includes
graphics and tables.
HyperText Markup Language (HTML) is the
language of the WWW. It is a common language that all web browsers are
designed to interpret the same way. An HTML file displayed in Netscape
on a Macintosh will almost match the look of an HTML file displayed in
Internet Explorer on a PC.
HTML allows the user to display formatted
text and graphics on a wide variety of platforms using a single file. It
also allows the user to link different files together using Hypertext
links. A hypertext link is an area of text or graphics that, when
clicked by a mouse, takes you to another area of text or graphics. The
next few sections of this handout will discuss how you can write HTML. |