Web Design in a Nutshell, 3rd Edition

Text as Data, Data as Text

It is easy to see even from our simple example how XML markup treats content in a text document like data. So while this document can be displayed in a page format, it can just as easily be stored in a database (which is a common use of XML-formatted information).

On the flip side, XML allows data to be stored in a plain-text format. This is the key to XML’s rampant success in the computing world. Data that had previously been stored in proprietary, device-specific formats can now be marked up in a text file and shared between incompatible systems. Longevity is improved as well. XML documents are self-defining, intuitive, and not tied to a format or system that may grow obsolete.