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The browser is the key or rather the window to the World Wide Web. It's main task is to display the formatted content of pages from the Web. This has to be done in a standardized way, defined by HTML. However, there are differences in how the content is presented on the computer screen depending on the local configuration. The operating system, screen resolution, available fonts, graphics capabilities and last but not least the browser itself determine how the Web is presented to the user.

That is why during the design and development of a Web site, it should always be viewed with different browsers on different platforms at different screen sizes and resolutions to obtain reliable results in any environment.

The first browser developed by Tim Berners-Lee was written for simple text terminals. At that time there were no fancy graphics or interactive web pages. ``lynx '' is such a browser. Its main advantage is that it can be used on dumb terminals and displays no images. The latter is an advantage for low bandwidth connections and makes lynx one of the fastest browsers. Nevertheless, it supports even forms, frames, which are displayed separately, and Client-Side-Image-Maps. Though, its the graphics capabilities and interactivity, which make the Web so attractive. Mosaic and its descendant Netscape Navigator were the first browsers to display text and inline images. Later, almost too late, Microsoft moved in and developed the Internet Explorer. Due to Microsoft's aggressive marketing it became the only serious competitor to the Navigator. All other browsers like Arena , Chimera , Cello , Amaya , or Opera remained niche products. Arena was developed by the W3 Consortium as an example for the full implementation of the HTML 3.2 standard. It supported new tags for mathematics markup, including subscripts, superscripts and Greek symbols. However, it is not updated any more and maths markup has not proliferated across the Web. Its successor is Amaya , a test-bed browser/authoring tool for HTML 4.0 . Jigsaw is its counterpart on the server side. It is an object-oriented Web server written entirely in Java.


HTML Documents are simple ASCII files. Thus, they can be created and edited with any text editor. Since HTML is a kind of ``programming language'' there are extensions for many programming editors for HTML syntax. ``NEdit'', a standard GUI style text editor for Unix, uses syntax highlighting to distinguish different elements in structured files. In HTML documents, for example, all tags are coloured and therefore the code is easier to read and understand.

``asWedit '', a special HTML editor, has a built-in parser to check the syntax for HTML 3.2 conformity. In addition text formatting is facilitated by a button bar and automatic insertion of formatting tags. Finally there a more or less accurate WYSIWYG editors. These editors display HTML documents almost like a browser and include many features of modern text processing applications. Netscape delivers the Gold editions of Navigator and Communicator with this type of editor. Microsoft's pendant is Frontpage , HotMetal is an often recommended editor. The editor of choice depends on programming experience, frequency of use and personal preferences. WYSIWYG editors hide all HTML coding behind their user friendly interface. However, many editors still have problems with complicated combinations of frames, tables and images, producing undesired results when viewing the pages with a real browser. Therefore users with programming experience often prefer usual programming editors.

Finally, the syntax and HTML conformity can be checked with HTML validators. The ``official'' HTML checker is the W3C HTML Validation Service . WebTech also provides a validation service. Having validated one's HTML documents ensures that less permissive browsers, which do not excuse forgotten closing tags for instance, will render the document as expected. Nevertheless it is always a good idea to check the results with various browsers also on different hardware and operating systems.

next up previous contents
Next: HTML Documents Up: Presentation on the World Previous: Networking
Werner Scholz