|Lesson 3||Markup language characteristics|
|Objective||Describe the Characteristics of Common Internet Markup Languages|
Markup Language Characteristics
Markup languages make our current version of the Internet possible.
Markup languages describe how text is to be displayed on a Web page or in a printed document.
In a markup language, the instructions are in the form of a set of tags or special characters.
For example <Bold-On>Hello<Bold-Off> are markups, officially called tags, that will cause the word Hello to appear in bold.
Markup languages do not provide interactive functionality. They serve as containers for text and graphics.
View the page source of any page on the Asteron home page as an example of markup languages.
To see the page source, in your browser, go to the View pull-down menu, then select Source or Page Source.
Growth of markup languages
The table below lists several markup languages and briefly describes their characteristics. Note that these markup languages are listed in the
order in which they were created, thus each new language includes new functionality.
SGML (Standard Generalized Markup Language) was developed to identify how markups, called tags, could be used to enhance text and graphics. The SGML standard doesn't specify tag names or use, it just specifies rules for how such tags will work. This permits subset languages to develop tag names and functions appropriate to their objective. For example, popular markup languages used in Web pages are HTML, DHTML, and XML.
How tags work
XML (Extensible Markup Language) is rich in formatting commands and commands for the sharing of information
between applications. It simply uses markups (also called tags) to specify how text, sentences, paragraphs, or files are to be handled for display or transfer to another system.
Finally, DHTML (Dynamic Hyper Text Markup Language) uses tags to identify where a dynamic action is to occur on a Web page.
For example, a rollover button may change color when the mouse is moved over it. Or clicking on the "Total My Shipping" button might
cause a recalculation of shipping costs. Thus, tags trigger a small program to permit a processing operation to occur.
What are the benefits?
The strength of any markup language is its ease of use for the user. For example, some users found
WordPerfect much easier to learn than MS-Word because it used markups to format the document.
However, a mature language like XML contains a thousand tag names, which takes a long time to learn.
What are the difficulties?
The biggest drawback to markups is they tend to be slower than other languages and tend to be quite tedious to write.
Another point of contention is that, because SGML never specified tag-naming conventions, just rules for implementation,
there is no uniformity of tag names for similar purpose. One markup language may use a <Center> tag and another may name their tag <C>
to perform the same centering function.
In the next lesson, you will learn about scripting languages (the fifth type of language) and their uses on the Internet.
Click the link below to strengthen your knowledge of the variants of markup language.