Namespaces are the way to organize programming code. It removes the chances of name conflict. It is quite possible to have one name for an item accidentally in large projects those results into conflict. By organizing your code into namespaces, you reduce the chance of these conflicts. You can create namespaces by enclosing a class in a Namespace...End Namespace block.
You can use namespaces outside your project by referring them using References dialog box. You can use Imports or using statement to the code file to access members of the namespaces in code.