XML introduction

XML is a markup language structured in the form of tags (much like HTML). The full name of the XML abbreviation is eXtensible Markup Language, so it is an extensible language or meta-language. The purpose of XML is to allow other languages to be defined on the basis of a standard language.

The structuring in an XML language is quite intuitive once the concept is understood. A validation is there to allow to define the constraints on the structure that the document will have to respect. Two concepts are possible for the validation process: DTD (Document Type Definition) and XML Schema.