Hi Guys, We all know that  Interface members are by default  Public and Abstract. But can we declare Interface as private or protected ?

If yes then what is the significance of Private Interface and is there any difference in implementation of Protected and Public Interfaces?

Interface members aren't 'public' or 'abstract'. They are just interface members. They're part of a contract. You can't set accessibility modifiers on interface members at all. Try it and you'll see the compiler errors!

Interface members are default implicitly public as all methods/properties e.t.c have to be implemented to the classes which inherited from it.

[As all have to be implmented so all are abstract] 

An Interface is a reference type and it contains only abstract members. Interface's members can be Events, Methods, Properties and Indexers. But the interface contains only declaration for its members. Any implementation must be placed in class that realizes them. The interface can't contain constants, data fields, constructors, destructors and static members. All the member declarations inside interface are implicitly public.

check http://www.codersource.net/csharp_tutorial_interface.html 

and http://forums.msdn.microsoft.com/en-US/netfxbcl/thread/55256ccb-3725-41c7-bc58-a7e05b3c0db9/