Why XML, Not HTML?

• Authors using XML are free to invent markup elements and document types tailored to a specific audience
• Content can be richer and easier to access, because of XML's superior hypertext linking abilities
• XML provides better facilities for browser presentation and performance
• XML's more flexible markup can be used by any XML software
• XML removes many of the complexities of SGML
• Valid XML files can also be used outside the Web, in an SGML environment

XML was created so richly structured documents can be used over the Web. The only viable alternatives, HTML and SGML, are not practical for this purpose.

HTML conveys nothing about the meaning of the marked up document. It comes bound with a set of semantics and does not allow arbitrary structure. SGML provides arbitrary structure, but is too difficult to implement for a web browser.

XML cannot be expected to completely replace SGML. Full SGML systems solve large, complex problems that justify their expense. However, it has been said that XML provides 80% of the benefit of SGML with 20% of the effort. In many organizations, filtering SGML to XML will be the standard procedure for web delivery.

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