XML stands for extensible markup language. This is a computer markup language that is almost like an extensible version of HTML. Crafted by the World Wide Web Consortium (W3C), XML is responsible for setting up the guidelines for the creation of a document. It also adds context to the data available inside the document. However, it is important to note that XML does not show how the data should be displayed.
There are some programs available in the market that extract information from an XML document. But before that could be done, the description of the document must be acquired and provided to the program. In order to get that, DTD, which is another computer language, is used to achieve that desire.
It is said that XML was created to simplify, generalize and make usable data over the Internet. It is a textual data format and to be translated to different languages around the globe, it must use Unicode. XML is designed mainly for documents but is also used for arbitrary data structures and web services.
As of now, there are hundreds of computer languages developed that are based on XML. Some of these languages developed include XHTML, SOAP, Atom and RSS. This form has been the basis of other XML-based formats. It has also been the default for many productivity tools popular in different offices. Some of this include Microsoft Office which is based of Office Open XML, OpenOffice.org which is based on OpenDocument and iWork created my Apple.
Several APIs (application programming interfaces) were created where in software developers can process XML data.
From XML 1.0 came many other variations and technologies. Some of this include XML Namespaces, XML Base (defines the xml:base attribute), XML information set or XML info set, Xpath, XSLT, XSL Formatting Objects, XQuery, XML Signature and XML Encryption.