Can you explain the concept of polymorphism in object-oriented programming?

Polymorphism in object-oriented programming is the ability of objects of different classes to respond to the same messages (method calls) in different ways. This allows using a single interface to work with different types of objects.

Example in Java:

class Animal {
    void sound() {
        System.out.println("Some sound");
    }
}

class Dog extends Animal {
    @Override
    void sound() {
        System.out.println("Bark");
    }
}

class Cat extends Animal {
    @Override
    void sound() {
        System.out.println("Meow");
    }
}

public class Main {
    public static void main(String[] args) {
        Animal a1 = new Dog();
        Animal a2 = new Cat();
        a1.sound(); // Outputs: Bark
        a2.sound(); // Outputs: Meow
    }
}

Here, the sound() method is called on objects of type Animal, but the behavior depends on the specific subclass — this is polymorphism.