A markup language is a computer language that separates the elements of a document by tags. Unlike programming languages, it is in human-readable format and can be opened with almost all text editors. For its nature of defining elements by tags, such a file allows definition of wide range of elements. These tags doesn’t have anything to do with the graphical representation of the data, nor they are used to specify user defined settings such as fonts, dimensions, etc.
There are quite a number of markup languages available for use these days. Some of these are discussed here for general awareness.
HTML – Hypertext Markup Language
XML – Extended Markup Language
XML stands for Extensible Markup Language that is similar to HTML but different in using tags for defining objects. The whole idea behind creation of XML file format was to store and transport data without being dependent on software or hardware tools. Its popularity is due to it being both human as well as machine readable. This enables it to create common data protocols in the form of objects to be stored and shared over network such as World Wide Web (WWW). The “X” in XML is for extensible which implies that the language can be extended to any number of symbols as per user requirements. It is for these features that many standard file formats make use of it such as Microsoft Open XML, LibreOffice OpenDocument, XHTML and SVG.
XHTML – Extensible HyperText Markup Language
The XHTML is a text based file format with markup in the XML, using a reformulation of HTML 4.0. These files are well suited to be open or viewed in a web browser. XHTML was designed to be more structured, less scripting, generic; using all the existing facilities of XML and more device independent. XHTML provides a generally worthwhile set of elements and attributes, with extension options in combination with style sheets. The attributes are used from the metadata attributes collection. XHTML provides flexibility and accessibility by subordinating all HTML presentation elements to style sheets. Style sheets are more versatile than these presentational elements. Specifications for HTML 4.01, HTML5 and XHTML are being dynamically developed by the World Wide Web Consortium (W3C).
XAML – XML based Markup Language
XAML, Extensible Application Markup Language, extension files describe the user interface elements for software applications based on Windows Presentation Foundation (WPF). Though a language, it doesn’t require to be programmed as it is based on standard format of XML which is easy to use and understand. XAML (pronounced as “zammel”) was developed by Microsoft with specific aim for creating user interfaces. Its acronym original stood for Extensible Avalon Markup Language, where Avalon was the code-name for WPF. XAML files are sometimes saved with XOML extension as well.
Few other markup languages include MHTML, HTM and XOML that use the base markup languages discussed above for their functionality. The use of respective markup language depends on the purpose. If the content is to be used for display purpose, then HTML, MHTML and HTM are used. However, if data description is the need, markup languages such as XML and those based on XML are used.