What is XML?

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XML is a technical term for the feed format created by the Web Feed Generator. XML is a way of marking text so that its meaning is distinct and information can be picked out and processed by computer software.

XML is like a set of Russian dolls where text can be nested at each level. The text in a book is in chapters, a chapter contains paragraphs, inside paragraphs there may be sections of emphasis.

XML can also be thought of as a tree representation of data; in a large corporation there may be several divisions or branches, each branch may have departments and the staff are like leaves on the tips of the finest branches.

<book>
  <chapter id="Chapter1">
    <title>
      Chapter 1
    </title>
    <paragraph>
      This chapter starts with an <emphasis>important</emphasis> example ...
    </paragraph>
    <paragraph>
      ...
    </paragraph>
  </chapter>
  <chapter>
    <title>
      Chapter 2
    </title>
    <paragraph>
      This chapter refers to <link target="Chapter1">chapter 1</link> ...
    </paragraph>
  </chapter>
</book>
      

XML provides a standard format for recording information in this way, but it does not say how the parts should be named and which go inside another. This means that different types of XML can be designed for special purposes, yet still conform to the fundamental nesting and branching rules.

Web pages can be written in a type of XML called XHTML. The news feeds provided by Metacentric are a type of XML called RSS, and the metadata feeds are known in the jargon as RDF. Ultimately, these details are far less important than what these services actually do.

See also:

• What is RSS?
• What is XHTML?