1.11. Extensible Markup Language (XML)

As the popularity of the web exploded, HTML’s limitations became apparent. HTML’s lack of extensibility (the ability to change or add features) frustrated developers, and its ambiguous definition allowed erroneous HTML to proliferate. The need for a standardized, fully extensible and structurally strict language was apparent. As a result, XML was developed by the W3C.

Data independence, the separation of content from its presentation, is the essential characteristic of XML. Because XML documents describe data, any application conceivably can process them. Software developers are integrating XML into their applications to improve web functionality and interoperability.