What is the purpose of empty class in Kotlin?

Question

I was going through Kotlin reference document and then I saw this.

The class declaration consists of the class name, the class header (

Answer 1

Sealed classes, in a sense, an extension of enum classes: the set of values for an enum type is also restricted, but each enum constant exists only as a single instance, whereas a subclass of a sealed class can have multiple instances which can contain state. reference