Why and where abstract methods & classes and static methods used?

[ajaysharma]

Hello to all ,
Actually I know how to declare and implement abstract method's and classes and static method's,
But the confusion is that where is exactly used ?? as i got this question in interview also,
just wanna know where it is exactly used and why is needed .
as we declare abstract method in super class and implement in subclass ,but we can do this in subclass also without declaring in super class why and where is needed,
please reply me soon??

[Fubarable]

Duplicate question. Locked.