Is data lost in down casting?

From what I know explicit casting is required when data is lost in the conversion process:

In the following, the casting operator () is required because the fractional portion (data) is lost in the conversion process: (int)6.88

However, in regards to downcasting, because the casting operator () is required to perform downcasting… is data lost? If so, what kind of data is lost? (Dog)new Animal()

public class Animal
{
    // some code
}


public class Dog : Animal
{
    //some code
}

>Solution :

In case of class (reference type) you manipulate with reference and reference is still the same when you cast:

   // reference created 
   Dog dog = new Dog(); 

   // Reference is still the same, by you see it as Animal
   Animal animal = (Animal) dog;

   // Cast back to dog. The reference doesn't change, now you see it as Dog
   Dog myDog = (Dog) animal;

Note, that creating Animal (base class) and casting to Dog (derived class) is an error:

  Animal animal = new Animal();

  //  Here Animal can't be cast to Dog  
  Dog dog = (Dog) animal;

And you’ll have run time error:

System.InvalidCastException: ‘Unable to cast object of type ‘Animal’ to type ‘Dog’.’

When casting to derived type you can use pattern matching:

 if (animal is Dog myDog) {
   // reference animal can be cast to Dog - myDog
 }
 else {
   // cast is impossible
 }