The abbreviation XML refers to the Extensible Markup Language, which is used to display hierarchically structured data in text file format. XML is also used to exchange data that is independent of platforms and implementations between computer systems.
The features of XML
The XML specification defines a metalanguage, which in turn determines application-specific languages through content and structural constraints. The restrictions are expressed by XML or DTD schemes. Examples of XML languages include MathML, RSS, GraphML, XAML or GPX, as well as the XML schema itself. An XML document consists of the text characters of the UTF-8 encoding. It is possible to view and edit XML in all editors that support UTF-8. If an XML document contains binary data, then this data must be encoded as text, for which different encoding types can be used. For XML documents, the element is considered to be the main structural unit, with the elements containing both text and other elements as content. The name of an XML element can be defined freely in the XML documents without DTD. In XML documents with DTD, the element names must be displayed in the DTD and the element must be in a position that is allowed in the specification tree. The content of each element is defined in the DTD. The elements are considered as information carriers of an XML document,
The story of XML
XML was born out of the reason that the HTML programming language has reached its limits at some point.
Although HTML has done a great deal, its limitations were evident early in the Internet, and it soon became apparent that it needed a language that could be used to define arbitrary tags universally. With SGML, while there was a longer, more universal document language, from which HTML was derived, by the way, it turned out to be too complicated for the Web. With XML, a very lightweight document language has been developed, which is arbitrary extensible. XML is used to easily define your own tags, whereby the appearance, unlike the meaning that is not defined, is firmly defined. A tag either stands alone or encloses an area, where tags have one or more parameters or none at all. The parameters are given values that are enclosed and assigned with specific commands. The tags can be nested within each other and the data thus structured hierarchically.
Basically XML can be used for any kind of description, storage or exchange of data. The advantages of XML are the widespread use and the associated low learning effort, the popularity and the easy readability for machine and humans. Compared to a proprietary binary format that is compact, the greater memory requirements and sometimes slower processing are among the disadvantages. However, both aspects are barely relevant today, so the benefits outweigh and XML has been able to establish itself accordingly in many areas.
Among the different areas of application include the use of new tags for writing documents as well
that different output formats can be generated from the same XML page and the web page creation can be done with separation of design and programming.