When to use Interface ?

* Interfaces are better suited to situations in which your applications require many possibly unrelated object types to provide certain functionality.
* Interfaces are more flexible than base classes because you can define a single implementation that can implement multiple interfaces.
* Interfaces are better in situations in which you do not need to inherit implementation from a base class.
* Interfaces are useful in cases where you cannot use class inheritance. For example, structures cannot inherit from classes, but they can implement interfaces.