Learn XML

           About XML . . .

XML stands for Extensible Markup Language

XML is a markup language much like HTML

XML was designed to carry data, not to display data

XML tags are not predefined. You must define your own tags

XML is designed to be self-descriptive

XML is a W3C Recommendation

 

Below is the example of XML document :

XML does not do anything. It was created to structure, store, and transport information.

The Difference between XML and HTML

XML	HTML
displaying information	carrying information

XML is not a replacement for HTML.

XML and HTML were designed with different goals:

• XML was designed to transport and store data, with focus on what data is
• HTML was designed to display data, with focus on how data looks

 

 

• XML documents form a tree structure that starts at "the root" and branches to "the leaves".
• Below is the example of XML document and simple syntax :

XML documents use a self-describing and simple syntax:

• The first line on the above example is the  XML declaration.
• The highlighted word describes the root element of the document (like saying: "this document is a   note"), while the code in the middle describe 4 child elements of the root (to, from, heading, and body).

XML Document Form a Tree Structure

 

• XML documents must contain a root element. This element is "the parent" of all other elements.
• The elements in an XML document form a document tree. The tree starts at the root and branches to the lowest level of the tree.
• All elements can have sub elements (child elements):

This an example of tree structure :

• To view more detail about XML tree structure you can visit this web XML Tree structure .

• In HTML, some elements do not have to have a closing tag :

                 <p>This is a paragraph.

                < br>

 

• But in XML, it is illegal to omit the closing tag. All elements must have a closing tag:

 

                <p>This is a paragraph.</p>
                < br />
 

•  XML tags are case sensitive. The tag <Letter> is different from the tag <letter>.
• Opening and closing tags must be written with the same case :