Where must I utilize XML

Question

Where must I utilize XML?

Answer 1

Its goal is to allow generic SGML to be served, received and processed upon the Web in the way which is now possible along with HTML. It has been designed for ease of implementation and for interoperability along with both HTML and SGML.

In spite of early attempts, browsers never permitted other SGML, only HTML (though there were plugins), and they permitted it (even encouraged this) to be broken or corrupted, which held development back for over a decade by making this impossible to program for this reliably. XML fixes which by making this compulsory to stick to the rules, and with making the rules much easiest than SGML.

But XML is not now for Web pages: actually it's very rarely used for Web pages upon its own since browsers still don't give reliable support for formatting and transforming this.