Many Web pages today
are poorly written. Syntactically incorrect HTML code may work in most browsers
even if it doesn't follow HTML rules. Browsers employ heuristics to deal with
these flawed Web pages; however, Web-enabled wireless devices (such as PDAs) can't
accommodate these hefty Web browsers. The next step in HTML's evolution comes
in the form of XHTML (eXtended Hypertext Markup Language), which is basically
a combination of HTML and XML.
XML,
the eXtended Markup Language, is a successor for SGML. More general than html,
it incorporate data inside tags themselves and has unlimited description capacities.
The format of the display is independant, and given by another document, the XSLT.
Rules to create tags are defined by another document, the DTD (Document Type Declaration)
which describes the grammar of the tags.
Xml
features - Significant tags based upon the content of data. - Separated
document used for the presentation.
Why
to use Xml? This is a standard and universal data format. It allows to
reuse a presentation for different data or use different presentations for same
data.