CSE3325: Behind the (World Wide) Web

In the previous lecture:

In this lecture:

What is the World Wide Web?

What is the Internet?

What is TCP/IP (Transmission Control Protocol/Internet Protocol)?

TCP/IP is a low-level protocol by which Internet computers of different makes, models and operating systems communicate.

Why be connected to the Internet?

The optimist: You want to share information or you find it interesting!

The cynic: You think its trendy, it looks good on your resume or you think you can make money.

Post-2000: The WWW is as ubiquitous as television was in the 80s. You're on it, or you're nobody!

How do you retrieve information from the Internet?

Use one of the (many) high-level protocols and its software user interface.

As well as Gopher, WAIS... find out what these are by doing a little web surfing!

How is information stored on Internet computers?

There are thousands of different file formats.

A file format is a particular way of storing or ordering information in a file.

The specification of a file format includes information regarding what goes into a file, and the order it is written/read.

GIF, PICT, PIC, PNG, RGB, SGI, TGA, BMP, PSD, RAW, SUN, TIFF... all of these are file formats for images (and there are many, many more)!

Common file formats.

You can look up some file formats. Here are some you might find on the web:

  • PostScript / EPS

  • RTF

  • LaTeX

  • troff

  • SGML

  • PDF

  • Plain text

  • Proprietry word-processor formats
  • AIFF - a sound file format

  • GIF - an image file format

  • Quicktime - a movie/video/animation file format

  • VRML - Virtual Reality Markup Language file

...the list goes on and on.


A particular file could be a:

...or almost anything else!


For every file format out there, you might need a special piece of software just to view / hear / play / read / interpret it!

Summary of the problems for Internet information retrieval:

  1. Q. Where do I look?

  2. Q. What software do I use to look for and retrieve the files?

  3. Q. How do I use that software?

  4. Q. What file formats do I need to be able to interpret/decode to find the answer?

So where does the WWW fit into all of this?

The WWW began in 1989 at CERN lab to help simplify the retrieval of information from the net.

The idea underlying the WWW is that a user is able to transparently jump around the global Internet retrieving information without worrying about the 4 problems posed above.

Now, to answer the questions above...

  1. Q. Where do I look?
    A. The WWW

    The Web glosses over the hundreds of individual computers, directories etc.

  2. Q. What software do I use?
    A. A Web browser

    Only a single piece of software! The browser communicates using several high-level protocols and eliminates the need to master numerous pieces of software.

  3. Q. How do I use the software (web browser)?
    A. By clicking the mouse on hyperlinks or selecting them from a menu.

    What could be simpler? Previously, software was used by typing cryptic commands into command-line user interfaces.

  4. Q. What file formats do I need to decode?
    A. None, the web browser handles that for you!

    The modern browser will (with the help of plugins and helper-applications) display images, play sounds, layout text and interpret a diversity of file formats without you needing to lift a finger!

Example Web sites

  1. Search engine (a good place to begin!)

  2. Home page

  3. Business page

  4. Art gallery, museum or cultural site

  5. Find your own sites and look at those for exercise 1.


This lecture's key point(s):

CSE3325 courseware | CSE3325 lecture notes

©Copyright Alan Dorin 2005