In C#, a delegate is a type that represents a method signature. Delegates allow you to treat methods as objects, which can be passed as arguments to other methods or stored as variables. Delegates provide a way to implement the observer pattern and to write callback functions.

public delegate void MyDelegate(string message);
public class MyClass
{
  public void MethodA(string message)
  {
      Console.WriteLine($"MethodA: {message}");
  }
  public void MethodB(string message)
  {
      Console.WriteLine($"MethodB: {message}");
  }
}
public class Program
{
  public static void Main()
  {
      MyClass obj = new MyClass();
      MyDelegate del1 = new MyDelegate(obj.MethodA);
      MyDelegate del2 = new MyDelegate(obj.MethodB);
      // Call the delegate with different messages
      del1("Hello");
      del2("World");
  }
}

In this example, we define a delegate named "MyDelegate" that takes a single string parameter and returns void. We also define a class "MyClass" that contains two methods, "MethodA" and "MethodB", that match the signature of the delegate.