Well-Formed Documents
An XML document is said to be well-formed if it
follows all the rules.
An XML parser is used to check that all the rules
have been obeyed.
Recent browsers such as Internet Explorer 5
and Netscape 7 come with XML parsers.
Parsers are also available for free download
over the Internet.  One is Xerces, from the
Apache open-source project.
Java 1.4 also supports an open-source parser.