Introduction of XML

XML is Extensible Markup Language
Extensible Markup Language (XML):
 Extensible Markup Language (XML) has very simple, yet strict syntax rules. To use XML efficiently and create well-formed XML documents, you need to become familiar with the document structure and components. This lesson introduces the XML document and focuses on how to create well-formed documents.

XML is a markup language that provides a universal format for structured documents and data on the Web.
Although XML documents look similar to HTML documents, they are very different.
HTML is a markup language that is primarily used for formatting and displaying text and images in a browser.
XML is a markup language for structuring data rather than formatting information.
You use XML to create a document that contains structured data that can be used or interpreted by other applications. The format or structure is straightforward and can be used by any person or program that can read text.
Unlike HTML, the tags in XML are extensible, and so you can create your own tags as you need them. HTML has a set of predefined formatting tags that you can use, but you cannot create your own.
XML is part of the World Wide Web Consortium (W3C) standards.
Note: XHTML is a more refined version of HTML. XHTML stands for “Extensible Hypertext Markup Language.” For more information, see the section titled “Comparing XML and HTML.”
Example:



 
    120
    Weiss
    8000
 
 
    121
    Fripp
    8200
 

Example: A Simple XML Page
The slide example of a simple XML document uses nested elements to describe employee data. Elements are identified by tag names such as employee, employee_id, and last_name. Tag names are distinguishable as markup, rather than data, because they are surrounded by angle brackets (< and >).
Note: In XML, an element includes a start tag (), an end tag (), and all the markup and character data contained between those tags.