EXtensible Markup Language (XML) is a language of free license that is used to store data in a legible way. It emerged from the necessity of storing a huge quantity of information. It is thought to be a universal standard for exchanging information structured between different platforms.
Some basic points about XML:
- It is not a markup language.
- It is a meta-markup language as it is used to describe metadata through markup tags.
- It provides a set of simple rules for designing text formats that allow to structure data.
- XML provides a uniform method to describe and exchange structured data.
- Describes structure and semantics, not format. This language not only presents the content of a text, but also gives it meaning, apart from the fact that the content of a document is separated from any presentation.
- The basic structure of an XML document consist of: Tags (they are in angle brackets < >) and attributes (of the name form =”value”)
- XML emerged from the HTML language. HTML is a format language to present web pages that are interpreted by the browsers. While HTML specifies what each tag and attribute mean, as well as its visualization; XML uses tags just to delimitate data blocks, and its interpretation is done by its processor. In other words, the <p> tag of an XML file is not thought to be a paragraph. It depends on the context.
- It is an eXtensible language, that is, unlike HTML, it allows to define tags and a self structure of the document through a set of defined rules in a DTD (Document Type Definition) document.
- XML is an open format that can be interpreted by any application that recognizes its language.
XML represents the present and the future in the web.