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eXtensible Markup Language

eXtensible Markup Language or XML is

• simplified form of SGML
• has been developed through agency of W3C
• omits more complex and less-used parts of SGML

XML

• is really metalanguage to design a markup language
• supports customisation and extension

XML is designed to make it easy and straightforward to

• use SGML on the Web
• define document types
• author and manage SGML-defined documents
• transmit and share them across the Web

XML removes two constraints holding back Web developments

• dependence on single, inflexible HTML document type
• complexity of using full SGML

XML allows DTDless or standalone document which requires

• matching start and end tags unless marked as empty
• proper nesting of tags
• no isolated markup characters (< or &)