VITTA Networking CD - web browsers

networking curriculum
support CD for senior
secondary studies

Topics
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. Networking History
. Why network?
. OSI model
. Connecting up
. Protocols
. Technology
. Network types
. Topologies
. Issues
. Design factors
. Economic effects
. www links
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networking > why set up a network? > browsers

Browsers

A web browser is a program that translates Hypertext Transfer Protocol (HTTP) ("world wide web" or WWW) data into information that can be read by human beings. Web pages are usually stored in Hypertext Markup Language (HTML), which is plain text with "tags" or formatting codes embedded in them to describe how they should appear.

For example, a page containing:

   <B> This is bold text </B> and <I> this is italic </I> 
    so you should <A HREF="index.htm"> visit this page </A >

would appear in a browser as:

This is bold text and this is italic so you should visit this page.

If the browser user clicked anywhere in the words "visit this page", they would be taken to another page called "index.html" (in this case, back to the index of the Why Network section of this CD).

One of the first web browsers was Mosaic. It gave rise to the main browsers of today: Netscape, (which has recently given birth to Mozilla), Microsoft's Internet Explorer and Opera.

All browsers are designed to translate standard HTML files into appropriate screen displays. The current HTML standard is version 4.01 and has been defined by the W3C organisation, but each browser designer tends to "tweak" the standards for extra functionality, sometimes resulting in HTML that cannot be understood by other browsers.

This can lead to pages that can only be viewed with a particular browser, which is not good if you want your web pages to be viewed by everyone, regardless of what browser, operating system or computer they are using. While both Netscape and Microsoft have been guilty of "innovative" tweaking of HTML standards, one usually finds that when a page does not appear onscreen at all, or looks completely wrong, a special Microsoft "feature" could be the culprit.

LINK: http://www.w3.org/MarkUp/Guide for a quick tour of HTML.

Web browsers are also responsible for decoding Javascript programming in web pages. Javascript (not to be confused with Java, the programming language), was invented by Netscape to make web pages "dynamic" and able to respond to different conditions. For example, if you put your mouse over a link, and the link changes visually, this is probably due to a Javascript 'rollover' routine. Most sophisticated web page editors such as Dreamweaver and Front Page automate such common Javascript programming for you.

Web browsers nowadays are all able to translate picture data and display JPG, GIF and PNG pictures in web pages. Most browsers also have built-in support for email and newsgroup (Usenet) message handling.

Common add-on features in web browsers are address books (to store lists of email contacts), bookmarks or favourites (to store the addresses of pages you want to visit again), 'spam' filtering, and security measures (such as digital security certificates) to prevent hackers getting into your system.

As browsers evolve, they include more features designed to cope with new trends. Mozilla, for example, now has built-in junk mail detection and the facility to block annoying pop-up windows.

Web browsers are an interesting slice of the software market. While most software is commercial (and often expensive), hardly anyone has ever paid to use a web browser. Once, Netscape was the king of browsers. In fact, since the demise of Mosaic on which it was based, it was the only browser. Some years later, Microsoft started the "browser wars" with the release of Internet Explorer, and since then most web browsers have all been free of charge to encourage people to use them. This trend seems unlikely to ever change. Now, in 2003, Internet Explorer is the dominant browser, but Microsoft knows that if they ever charged people to buy their browser, their dominance would immediately end.

Netscape, now owned by AOL, is still developing their Netscape Communicator browser but an offshoot, Mozilla, has been born. This is an "open source" browser developed by a community of programmers for free public use. "Open source" means that no organisation owns the programming, and anyone can download it and use it - it began with Linux, the famous open source version of the Unix operating system.

Freed from the corporate restrictions of having to make money, the Mozilla Project (http://www.mozilla.org) is once again proving to be a threat to Microsoft's dominance of the browser market. It produces versions for many computer platforms (including MacOS X, Linux, Windows, Solaris, Irix, BeOS, HPUX, and OS/2) and is developing its product at an ever-increasing rate thanks to the thousands of programmers contributing to the Mozilla Project.

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networking curriculumsupport CD for seniorsecondary studies

networking > why set up a network? > browsers

Browsers

networking curriculum
support CD for senior
secondary studies