Explain what is meant by an abstract method in object-oriented programming

An abstract method in object-oriented programming is a method declared in an abstract class or interface but without an implementation. It serves as a template that must be implemented by all subclasses of that class.

In C#, an abstract method is declared with the abstract keyword and does not contain a body:

abstract class Animal
{
    public abstract void MakeSound();
}

class Dog : Animal
{
    public override void MakeSound()
    {
        Console.WriteLine("Woof");
    }
}

Thus, an abstract method sets a mandatory contract for subclasses, ensuring polymorphism and enabling the creation of flexible architectures.