• If you want to specify special characters, many of which are not found on the keyboard, you can use the Unicode equivalent.  Use &# followed by a decimal, or &#x followed by a hexidecimal number that represents the Unicode character you wish to use.  These are called character references. Of course, not to be confused with people you bring to court to vouch for your character.
• Other characters are on your keyboard, but they already have meaning in XML.  This is often the case with HTML as well.  So, to show a < sign, use &lt; For a > sign, use &gt;  These are called entity references.
• If you want to include an entire string without having it marked up, preceed it by <![CDATA[ and end it with ]]>.  This is called a CDATA Section.
• Note that the first line of our XML file is:
<?xml version="1.0" encoding="ISO-8859-1"?>
This is an example of a processing instruction, which is enclosed with <? and ?> .
• Comments are just like the ones we see in HTML.  Enclose your comments in <!-- and --> .

 Parsing XML