Polymorphism allows the JVM to determine the method to invoke at runtime based on the object's actual type.
Polymorphism in Java is achieved through method overriding. When a subclass overrides a method from its superclass, the JVM determines which method to execute at runtime. For instance, if you have a superclass 'Notification' and subclasses 'EmailNotification' and 'SMSNotification', calling 'send()' on a 'Notification' reference will execute the appropriate subclass method depending on the actual object type.
Additional Notes
How does polymorphism enable runtime method selection in Java?