World Wide Web Concepts
Module W01c
About this Document
Contents
Clicking on the colored bar here and throughout the document will return you
to the Contents:
What is the World Wide Web?
- A way of using the Internet to find information easily and present it effectively
- Embodies the concept of hypermedia over a long
distance
- Originally developed by Tim
Berners-Lee
while
he was at the Conseil Européen pour la Récherche Nucleaire
(CERN, the European particle physics
research lab), Geneva, Switzerland. 
- The World Wide Web (WWW) consists of server computers which respond to
requests for information.
- The hypermedia is provided by a system of codes known as HyperText
Markup Language (HTML).
- You (the user) use a "web browser" to decode the
coded documents and show them on your screen.
- The World Wide Web is loosely organized by The
World Wide Web Consortium
- More information about the World
Wide Web...
What is Hypermedia?
- Text and Graphics containing "links" - hot spots connected to other
information
- In the text, some words are "hot" - usually either numbered or underlined
(as in this text)
- In the graphics, either pictures or parts of pictures are "hot"
- The user points to a link - using arrow keys or mouse
- A connection is made which brings the related information to the screen
- The concept of hypertext was brought forth by Ted
Nelson in 1965.
- Examples:
Getting Access to the World Wide Web
Getting on to the Web means attaching to the Internet, becoming a "client" and
using a browser. This section explains these concepts...
Clients and Servers
- A client is:
- a computer, running...
- a program, which...
- requests information in a particular way, from...
- A server, which is:
- a computer, running...
- a program, which...
- responds to requests for information.
- A Web site is:
- a server, running...
- a Web-server program, able to...
- send you files with HTML text and graphics
- A Web browser is:
- a computer program, which lets your computer be a...
- client on the World Wide Web.
That is, it requests information from a Web server and displays it when it arrives.
Locating Resources
- On the Internet, files have addresses known as Universal Resource
Locators: URL
- Example URL:
http://www.w3.org/WWW/HyperText/TheProject#Community
- Parts of a URL:
- Type identifier http:
- http: HTML file. HTTP is the acronym of HyperText
Transfer Protocol, the "language" used to request and handle
Web files.
- gopher: Gopher file
- file: local file on your machine
- Machine address //www.w3.org
- //www.w3.org an internet address
- ///c|web/wcc.gif a local file address
- File on the Internet
- /WWW/HyperText/TheProject points to the beginning of the
file
- #Community points to a "bookmark" within the file
Using a Browser
- A Web browser is a program that works as a Web-client on
your computer
- It lets you request information from Web servers
- When the information arrives, it interprets the HTML code and displays
it on the screen
For more detail about browsers, see "World Wide Web Tricks
and Tips," module W10c
Textual and Graphical Browsers
Some Web browsers are limited to showing text; most show both text and graphics
- Text-based Browsers
- The best-known is Lynx
- Advantages:
- Faster than graphics-based browsers: operates well on slower connections
(under 9600-baud)
- Can run over serial dial-up lines
- Often found on freenets and inexpensive commencial Internet services
- Available at no charge
- Disadvantages:
- Graphical information is not shown
- Some Web-sites display information and give hot-links primarily through
graphical images
- Graphical Browsers
- The best-known are Netscape Navigator, Mosaic, and Internet
Explorer
- New browsers occasionally emerge from other developers
- Advantages:
- Much more colorful and exciting than text-only browsers
- Useful information can be conveyed using graphics
- Some Web-sites give hot-links mainly in graphical images
- Disadvantages:
- Graphical images require a lot more time and network bandwidth
- 14.4 K-baud is the minimum speed required for productive work using
a modem
- When using a modem, a SLIP or PPP connection is required, but this
is now standard on computers and with Internet service providers (ISPs).
Browser usage is recorded by several institutions, including the University of
Illinois at
Champaign/Urbana. Get the latest figures at http://www.cen.uiuc.edu/bstats/latest.html.
Using Browsers by Modem
A text-based browser can be used with a serial modem connection. Graphical browsers
require that Internet Protocol be interpreted by the machine you are running -
in other words, your machine must become a (temporary) node on the Internet. This
requires a different "protocol": either SLIP or PPP.
- SLIP: Serial Line Internet
Protocol (older)
- PPP: Point to Point Protocol
(now preferred)
- Both require that your computer have the capability of handling low-level
Internet Protocol
- This must be handled at the operating system level with a specially installed
program that provides a TCPIP "stack".
- Stack = series of networking protocols to handle different
aspects of network connections.
- DOS: using a memory resident (TSR) program
- Macintosh: part of MacOS (before 7.5, using Mac TCP system extension)
- Windows: part of 95, 98, and NT; 3.1 using WINSOCK.DLL (available in
several versions)
- In order to use it, you must have authentication to use a network entry
point:
- Your browser asks the TCPIP stack to dial the phone for you.
- Your modem dials a number you have given it previously - the number you
ordinarily dial to reach your Internet service provider.
- If you have the right kind of account, the server will "authenticate"
you - that is, vouch that you have a right to use the network. (Note: if
it is a commerical service provider, the meter starts ticking!)
- You don't (necessarily) see your server's identification screens. You
see only the first Web site your browser is pointed at. You can then use
the Web freely.
- Setting up the required connection can be tricky - it depends on the configuration
of your machine, your modem, and the service you use, so no general instructions
can be given. Most Internet Service Providers have installation software that
attempts to simplify the process.
Getting Acquainted with Graphical Browsers
Mosaic, Internet Explorer, and Netscape
- Each have very similar features
- Mosaic was the original graphical Web browser, and changed
the character of the Web within less than a year of its appareance.
- Originally developed at University of Illinois and distributed as freeware
- Now no longer widely used
- Netscape is the most widely used browser
- Developed by some of the Mosaic people from University of Illinois who
formed their own company
- Now a very successful company
- Microsoft Internet Explorer, is gaining in popularity because
it is included free with Microsoft's Windows 95 and 98 operating system. (The
Department of Justice has sued Microsoft over alleged unfair business
practices in - among other things - distributing Internet Explorer.)
- Has most of the features of Netscape
- Adds new features of its own
- Microsoft and Netscape are seen as battling for supremacy on the World
Wide Web
Starting Options
All browsers can be set to start at any location you like. The location could
be...
- Company headquarters site for the browser (Netscape, CompuServe, Microsoft
Network...)
- A bookmark file you have created yourself
- An information finder you like to use.
(For information on how to do this, link to module W10c.)
Browsing Options
There are several options on how text and graphics appear when browsing. Check
the Options menu for how to change...
- Font
- Color of hot-links
- Whether graphics are loaded by default (not loading them is faster but
more boring)
- Whether graphics are shown as they load, or only after they
load
- ...and many other, more technical details (See module W10c)
Helper Applications
Files of many different formats, such as pictures, sounds, and video, can be sent
over the Internet. Browsers can't handle them all, so they call for help from
other programs that may be available on your computer. You can specify, for many
different file types, what program you have available to help. This is under the
Options menu.
For more information about how browsers work, see Module W10c
, "World Wide Web Tricks and Tips"
Browsing and Searching
There are two different ways to get information from the Web...
- Browsing
- Starting at a good location
- Following leads until you get something useful
- Like going to the library and looking through likely shelves for an interesting
book
- Good if you have a subject area to look in, but no exact words to look
for
- Hypermedia is ideal for browsing
- Searching
- Using a "search engine" to comb through a database for you
- Chasing down the leads that come up to you
- Like going to the card catalog in a library and looking for particular
subjects
- Usually more effective if you have words for what you're looking for
- Several effective search engines and databases are available through
the Web
- For more information about searching and browsing, see Module W12c,
"How to Find World Wide Web Sites".
Under the Hood: HyperText Markup Language
How does a Web browser do all the things it does for you? It interprets HTML...
- HyperText Markup Language is a code embedded in text files
- When you use a browser, you don't usually see it
- There is an option in most browsers to see it. Try it now!
- Netscape: the View menu, PageSource option
- Explorer: the View menu, Source option
- HTML can be typed directly into a text file with a word or text processor
- if you know HTML!
- Several HTML generators or "translators" are available. This HTML document
was created using Internet Assistant 1.0 with Microsoft Word (available free
from Microsoft) and revised by AOLpress and Netscape Composer. Others are
available either free or for a price; demos are often available as well.
(For more information about Web page authoring, see module W30c
"How to Create a Web Page using a WYSIWYG Editor".)
Audience and Objectives...
This is for people who want to know what the World Wide Web can do and how it
works from a user perspective. You need to know what the Internet is. (Module
NG02c will provide you with the needed background.)
When you successfully complete Module W01c, you will be able to:
- Explain the concept of hyperlinks
- Discuss the origin of the World Wide Web
- Describe World Wide Web
- Explain the difference between hypertext and hypergraphics
- Describe Client
- Explain what a "Web browser" is
- Discuss the difference between text-based and graphical
Web browsers, and the advantages of each
- Give examples of the more popular Web browsers, both
text and graphical, and the advantages of each
- Define HTTP
- Explain the difference between a serial link and
a PPP or SLIP link, and why PPP or SLIP is needed for graphical Web browsing
- Discuss the concept of clients and servers as applied
to the World Wide Web
- Explain the fundamental tools needed to start using
a Web browser
- Discuss startup options, graphics options, and helper
applications
- Explain how to browse and do basic searching on the
Web
- Define HTML
- Explain how HyperText Markup Language (HTML) is used to format and link
Web documents.
About this document...
Module W01c: World Wide Web Concepts
- Review:
W01cr
- Author:
- Laurence J. Krieg
- Institution:
- Department of Computer Information
Systems, Washtenaw Community College
- Date:
- Original version 20 November 1995
- This Revision:
Monday, 31-Aug-2009 11:48:00 EDT
Sponsored in part by CoNDUIT
CoNDUIT is a registered service mark of the Society
of Manufacturing Engineers. CoNDUIT is funded by the U.S.
Department of Energy under Cooperative Agreement No.DE-FC05-94OR22341, as
part of the Defence Advanced Research Projects
Agency's Technology
Reinvestment Project. Statements contained on these pages do not necessarily
reflect the views of the Department of Energy, DARPA, or the U.S. Government.
while
he was at the Conseil Européen pour la Récherche Nucleaire
(CERN, the European particle physics
research lab), Geneva, Switzerland.