Every class is derived from Object — even classes that we define ourselves!

When you create a class, C# implicitly makes it inherit Object. So when we write this code:

class Book
{}

C# assumes we mean:

class Book : Object
{}

Even if we already declared a superclass, like…

class Book : Media
{}

…Object will be at the top of the family tree. Maybe Media directly inherits from Object, or its base class inherits from Object, etc.

We can prove this to ourselves by attempting to convert any reference to an Object. None of this code will throw an error because each type — at some point — inherits from Object:

Object o1 = new Dissertation();
Object o2 = new Diary();
Object o3 = new Random();
Object o4 = new Forest("Amazon");

Value types and strings also inherit from Object:

Object o5 = 21;
Object o6 = false;
Object o7 = "Hello you!";