How to prevent a class from being inherited? Sealed in C#?

In order to prevent a class in C# from being inherited, the sealed keyword is used. Thus a sealed class may not serve as a base class of any other class. It is also obvious that a sealed class cannot be an abstract class. Code below...

C# Example
sealed class ClassA
{
public int x;
public int y;
}

No class can inherit from ClassA defined above. Instances of ClassA may be created and its members may then be accessed, but nothing like the code below is possible...

class DerivedClass: ClassA {} // Error

To know whats a sealed method in C# Click Here