Off late the Internet has exploded with a big bang into our lives. Web site creation is quickly becoming one of the fastest growing sectors. In the early days, Web site design consisted primarily of creating fancy graphics and nice-looking, easy to read Web pages.

As today's Web sites have become user interactive, the steps in Web site design have changed. Although creating a pleasant-looking Web site is still important, the primary focus has shifted from graphical design to programmatic design.

Consider a company wanting to sell its product on the Web. In such cases, the Web pages will collect and store user's billing information. This calls for storing and manipulating such data in a database. This is where XML comes into the picture.

Now let us enter XML, which could be the solution for various problems that might arise when using web with Database intrinsic web pages.

The term Markup is a concatenation of words mark up. This refers to the traditional way of marking up a document in the print and design worlds.

Markup is used to modify the look and formatting of text or to establish the structure and meaning of the document for output to some medium, such as printer or the World Wide Web. Markup consists of codes, or tags, that are added to text to change the look or meaning of the tagged text. The tagged text for a document is usually called the source code, for that document. Most word processors use some sort of markup languages to produce formatted text.

There are two types of Markup languages namely Specific Markup Languages and Generalized Markup Languages.

Specific Markup languages were developed for specific purposes. These markup languages cannot be used for any other purpose other than that for what it was developed for.

A markup language, namely Hypertext Markup Language or HTML, was designed for simplicity and with a flexible structure. It allowed text and graphics to be displayed in any web browser.

Many markup languages have served quite well as document formatting tools for printing on the web. However, they do not perform well in describing the data they contain or at providing contextual information for the data. For example, the Hyper Text Markup Language describes how the text should be formatted but conveys nothing about the kind of text data included in the document.

Specific Markup languages have the following limitations:
When using Specific Markup languages, the authors are limited to a particular set of tags. If these set of tags do not meet a need authors must find an alternative way to meet his needs. A Document might not be portable to other applications, as the data is not self-describing. It cannot be used for any other purpose than that for which it was originally intended. The language probably has a proprietary way of marking up text that is not compatible with other markup languages. This can create confusion and additional work for authors who must use several languages to accommodate different applications.

In the 1970's, Dr. C. F. Goldfarb and two of his colleagues proposed a method of describing text that was not specific to an application or a device. The method had two suggestions:

	The markup should describe the structure of a document and not its formatting or style characteristics.
	The syntax of the markup should be strictly enforced so that the code can clearly be read by a software program or by a human being.

The result of these suggestions was the SGML that was adopted as a standard by the International Organization for Standardization in 1986.

SGML has added provisions for identifying the characters to be used in a document. This makes it easier to ensure that a processor can understand everything in a document by allowing a document to specify the character set, which it uses.

SGML provides a way to identify objects that will be used throughout a document. These objects, called entities, are convenient to use when a text fragment or any other data appears in several places in a document. If an entity is declared in one place of the document, any changes to that declaration will be reflected in all occurrences of the entity throughout the document.

<!DOCTYPE FRUITS PUBLIC "//EXT/DTD CATALOG//EN">
<FRUIT>
<CITRUS> Orange
<PRICE> Rs.5.00
</FRUIT>

The Code snippet shown is an example of an SGML document. We can see that the content is the same as that of the HTML document. These similarities exist because HTML is an application of SGML. HTML was created using SGML standards. The main difference between SGML and HTML is that SGML is extensible, which means that it allows an author to define a particular structure by defining the parts that fit that structure. Whereas HTML is not extensible, which means that HTML cannot be used as a basis to create another markup language with its own rules and purposes.

XML is an acronym; it stands for eXtensible Markup Language.

XML is a computer language for describing information. You could say, HTML also describes information. But that is not true. XML improves on the HTML approach and makes the Web a better place to do business, to learn, and to have fun.

HTML is a great technology, and it has changed the world. However, a great deal of useful information is lost when data is converted into HTML. The information that, if preserved, can be used to build a whole new world of computer applications on the web. To clarify this point, look into the following code snippets.

<!--- HTML Snippet -->
<h1>Employee</h1>
<p>Name : Rohit
<p>Age : 25
<<! p>Designation : Marketing Executive

<! --- XML Snippet -->
<Employee>
<Name>Rohit</Name>
<Age>25</Age>
<Designation>Marketing Executive</Designation>
</Employee>

Now, if you view these code snippets from the computer's point of view, you would find that the XML document would be easier to process. XML captures the most useful information and has potential uses. This distinction is the very essence of XML.