C# .NET - Partial method,partial structure and partial Interface?

what are these Partial method,partial structure and partial Interface? when are they going to be useful?what role does these play in Entity framework(ORM)?

This isn't any more complicated than now being able to support breaking up these types into separate files.  Very similar to the concept of asp.net code behind files and their partner designer.cs files. 

"Partial" is used a lot with code generators of all sorts.  Enables you to customize what was generated.

So it is like an Interface which has the signature without implementation.However the subtle difference is all the methods of the Interface have to be implemented in the class that inherits the interface contract where as the partial method may or may not be implemented as the requirement of the project.please correct me if i am wrong.