It removes two constraints which were holding back Web developments:

a)Dependence on a single, inflexible document type (HTML) which was being much abused for tasks it was never designed for;

b)The complexity of full SGML, whose syntax allows many powerful but hard-to-program options.

XML allows the flexible development of user-defined document types. It provides a robust, non-proprietary, persistent, and verifiable file format for the storage and transmission of text and data both on and off the Web; and it removes the more complex options of SGML, making it easier to program for.

Keywords:XML,HTML,SGML,hard-to-program options,flexible development, robust, non-proprietary, persistent, verifiable file format , storage ,transmission of text, data, complex options ,, inflexible document