What is the Internet and what is the World Wide Web? Don't know? Then click here before reading this page.
A web browser is a piece of software designed to help us experience the world wide web in a user-friendly graphical way. The following are some of the functions a web browser performs ...
It translate the language of web pages (HTML documents) into viewable graphical pages
It translates the code of hyperlinks into clickable links
It de-compresses and displays JPEG images
It displays GIF and PNG images
It can run small JavaScript and Java applets (applications) to create advanced functionality and interactivity
It can facilitate communication between your computer and a server. eg To enable credit card transaction via scripting and programming languages like php and Java.
It determines how a non html file (such as a pdf, MP3, or AVI) should be handled.
It utilise's a system of installed plug-ins to handle non-standard or new file types which the browser cannot handle natively.
Popular web browsers include ...
Internet Explorer
Web browser software continues to develop with each new version offering added functionality and support for new web technologies and file formats. Web designers need to predict average end-user target systems by attempting to profile or determine their hardware (screen size, CPU etc) installed browser version and installed plug-ins.
Web browsers can handle relatively few types of data/file types on their own, therefore they utilise a system of additional program elements called plug-ins. These plug-ins are loaded (or integrate) with the core browser program when it is launched.
| Data/file types browsers can handle without plug-ins | Data/file types browsers NEED a plug-in to handle |
|---|---|
html, htm, all tags html text CSS .gif .jpg .png (not fully supported) JavaScript
|
Flash (.swf) Shockwave (.dcr, .dxr) Adobe Acrobat (.pdf) Video (all types) Word (.doc) Real Audio Audio (including .wav, .aif & MP3) Windows Media Quicktime movies etc |
Plug-ins are sometimes called File Helpers. Some plug-ins handle only one file type (eg Adobe Reader, Flash). Because some file types can be handled by a variety of plug-ins, Internet Explorer allows you to determine which files are handled by which plug-ins.

If a new plug-in/file format become popular enough they may be integrated within the source code of future browser versions.
Many plug-ins will be pre-installed on your machine, but if you're browser encounters a new file type it doesn't have a plug-in for, it may prompt you to download it.
None at present