Namespaces remove ambiguity from element type names. This assists the exchange of XML documents between users, but it also allows elements from different namespaces—in context implicitly different XML application languages—to be mixed in the same document.
You can mix elements in the same document if you understand the scope of namespaces.
The scope of a namespace is limited to all elements nested inside the element on which the namespace was declared. However, the namespace may be altered by a namespace declaration on any of the nested elements.
Look at a simple example:
<somePrefix:anElement xmlns:somePrefix= http://www.XMML.com/someNamespace> <anotherPrefix:anElement xmlns:anotherPrefix="http://www.XMML.com/anotherNamespace> ...