Introduction to XML

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 uses a Document Type Definition (DTD) or an XML Schema to describe the data
  • XML with a DTD or XML Schema is designed to be self-descriptive.
    • How is XML different from HTML?

    Markup languages generally combine two distinct functions of representing text (document)-the 'look' and the 'structure'. HTML and XML are complementary to each other.
  • XML fundamentally separates content(data and language) from presentation; HTML specifies the presentation.

    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, while XML is about describing information.

  • HTML explicitly defines a set of legal tags as well as the grammar (intended meaning). XML allows any tags or grammar to be used (hence, eXtensible)

    The tags used to mark up 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. The tags in the examples (like ) are not defined in any XML standard. These tags are "invented" by the author of the XML document.

  • XML is a complement to HTML. XML is not a replacement for HTML.

    For Web development it is most likely that XML will be used to describe the data,while HTML will be used to format and display the same data.
    XML is a cross-platform, software and hardware independent tool for transmitting information.

  • XML does not DO anything

    Maybe it is a little hard to understand, but XML does not DO anything. XML is created to structure, store and to send information.

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