Method overriding is important tool for acheiving polymorphic behavior.
If two or more methods with the same name and method same signatures are available where one method is in Parent (Super) Class and other method in Child (Sub) Class it is called method overridding.
Overridden methods must have same name and same number of parameters and same type of parameters. Overridden methods must have same return type. Overridden methods exist only in classes where classes are related with inheritance.