What is XML?
XML stands for EXtensible Markup Language. XML is a markup language for documents containing structured information.
Structured information contains both content (words, pictures, etc.) and some indication of what role that content plays (for example, content in a section heading has a different meaning from content in a footnote, which means something different than content in a figure caption or content in a database table, etc.). Almost all documents have certain structure.
A markup language is a mechanism to identify structures in a document. The XML specification defines a standard way to add markup to documents.
How Is XML Defined?
XML is defined by a number of related specifications:
Extensible Markup Language (XML) 1.0 defines the syntax of XML. The XML specification is the primary focus of this article. XML Pointer Language (XPointer) and XML Linking Language (XLink) defines a standard way to represent links between resources. In addition to simple links, like HTML's <A> tag, XML has mechanisms for links between multiple resources and links between read-only resources. XPointer describes how to address a resource, XLink describes how to associate two or more resources. Extensible Style Language (XSL) Defines the standard stylesheet language for XML.
The main difference between XML and HTML
XML was designed to carry data. XML is not a substitution for HTML.
XML and HTML were created with different goals:
1.XML was created to describe data and to focus on what data is about.
2.HTML was created to present data and to focus on how data looks.
In other words,HTML is about presenting information, while XML is about describing information.