Are modules analogous to namespaces in C# or packages in Java?

[Afshin]

Modules confuse me as a way to organize code.

If a module is composed of multiple classes, it seems that the 
module semantics in D encourages putting all those classes in one 
file.

Can someone explain how to organize a set of classes into a 
module (or namespace, or package) so that each class can have 
their own file?