HTML 4.0 - HyperText Markup Language
HyperText Markup Language (HTML) is widely used on the Web for adding
structure to text documents. Browsers interpret these documents, representing
the structure in media-specific ways to the user. For example, visual
browsers typically display the strong element (<strong>
... </strong>) as bold text, while text-to-speech
readers might emphasize that text when pronouncing it.
With the help of Cascading Style Sheets (CSS)
the author may define how structural elements are to be represented,
overriding the browser defaults.
XML 1.0 - Extensible Markup Language
Extensible Markup Language (XML) is a markup language like HTML,
but instead of having a single, fixed set of elements, it allows you
to define your own - or use a set made by someone else. It even allows
using multiple sets within a single document - by using XML
namespaces.
Some applications of XML, such as XHTML
and MathML, have already
become W3C Recommendations. Others are currently W3C Working Drafts.
Style sheet standards, such as CSS and XSL, offer a variety of options
for specifying how XML elements are to be rendered. Standards-compliant
support for direct rendering of XML is spotty in browsers, so for
presenting information to humans, HTML (or XHTML) with CSS-driven
styling is the way to go. XML is mostly used for machine-to-machine
communication today.
XML is more flexible than HTML, primarily because of the ability
to add your own elements and make your own structural systems. This
makes it an ideal format for the organization of large quantities
of data - it is already in use in many databases and search engines.
W3 standards
