Answer may be:

It is used to achieve abstraction. The template of the Interface has only method declaration. It does not have method implementation. Few points are needed to remember about the interface:

• all the methods declared inside the interface are by default public abstract void.
• all the variables inside the interface are by default public static final.
• It can only be implemented in classes, not extended.
• The methods will be implemented in the classes where the interface is implemented.