Default Namespaces : Namespace « Namespace « XML Tutorial

A default namespace is like a regular namespace.
You don't have to specify a prefix for all of the elements that use it. 

<person xmlns="http://www.java2s.com"> 
    <name> 
        <title>Sir</title> 
    </name> 
</person> 

You can declare more than one namespace for an element, but only one can be the default. 

<person xmlns="http://www.java2s.com" 
        xmlns:xhtml="http://www.w3.org/1999/xhtml"> 
    <name/> 
    <xhtml:p>This is XHTML</xhtml:p> 
</person>

2.1.Namespace
	2.1.1.	Why We Need Namespaces
	2.1.2.	How XML Namespaces Work
	2.1.3.	Default Namespaces
	2.1.4.	Declaring Namespaces on Descendants
	2.1.5.	Understanding URIs
	2.1.6.	Change URI of namespace
	2.1.7.	Using Prefixes