In this document, XML refers to the entire set of specifications and products related to a particular approach to representing structured information in text-based form. Specifically, the World Wide Web Consortium (W3C) has specified a markup-based language called XML. Closely related to HTML, XML was designed to build on what had been learned with that technology. Among other things, XML was designed to be much more generally useful than HTML, while exhibiting the simplest possible expression. HTML is about displaying information. It was designed to display data and to focus on how the data looks. XML, meanwhile, is about describing information. It was designed to describe data and focus on what the data is. Since XML's invention, a constellation of XML-related specifications has been produced and is in progress to leverage the power of this new form of information expression.
For the COBOL programmer, it is best to view XML not as a markup language for text documents, but rather as a text-based encoding of a general abstract data model. It is this data model, and its similarity to COBOL's data model, that yields its power as an adjunct to new and legacy COBOL applications needing to interact with other applications and systems in the most modern way possible.
XML is extremely important to the COBOL programmer for two key reasons. First, it is rapidly becoming the standard way of exchanging information on the Web, and second, the nearly perfect alignment of the COBOL way of manipulating data and the XML information model results in COBOL being arguably the best possible language for expressing business data processing functions in an XML-connected world.