This formatting language is built to contain data, and in a way so it's possible to see which data is which kind. An example:
<?xml version="1.0"?> <ship name="Georg Stage" fields="3"> <start x="4" y="3" /> <end x="4" y="5" /> <hit field="2" /> </ship>Here a ship is described, with name and length. It is also described where the ships starts and ends, and the one field hit is also there.
XML isn't born with any tags. If it's important to use the "right" tags, these can be defined in another document (DTD or Schema/XSD). A well formed XML document abide by the rules of correct embedding and ending. A valid document sticks to its definition.
That XML is good for keeping data can e.g. be seen by the facts that it's easy to 1) move a database to an XML document, 2) read and correct this document as a human being, 3) move the contents of the document to a new database.
Concept last updated: 08/09 2003.