As simple as XML namespaces are, they are so pervasive in Web services technologies that they warrant an explanation.
The purpose of XML namespaces is to prevent naming collisions in element and attribute names. An XML namespace is identified by a unique string that is used as a prefix to element and attribute names. 
 Do not confuse XML namespaces and .NET namespaces. They are similar in that both are used to prevent name collisions, but they come from different worlds and work differently.
For example, if you are building a project management application, you might use a <schedule> element to represent the project's schedule. An accounting application might also ...