XML Introduction

What is XML?

  • XML stands for Extensible Markup Language
  • XML is a markup language much like HTML.
  • XML was designed to describe data.
  • XML tags are not predefined in XML. You must define your own tags.
  • XML is self describing.
  • XML uses a DTD (Document Type Definition) to formally describe the data.

What is the main difference between XML and HTML?

  • XML is not a replacement for HTML.
  • XML and HTML were designed with different goals:
  • XML was designed to describe data and to focus on what data is.
  • HTML was designed to display data and to focus on how data looks.
  • HTML is about displaying information, XML is about describing information.

XML Tags

  • The tags used to markup HTML documents and the structure of HTML documents are predefined. The author of HTML documents can only use tags that are defined in the HTML standard.
  • XML allows the author to define his own tags and his own document structure.

XML is not a replacement for HTML. In the future web development, it is most likely that XML will be used to structure and describe the Web data, while HTML will be used to format and display the same data.

XML can be used to exchange data

In the real world, computer systems and databases contain data in incompatible formats. One of the most time consuming challenges for developers has been to exchange data between such systems over the Internet. Converting the data to XML can greatly reduce this complexity and create data that can be read by different types of applications.