In Kotlin, a sealed class is a class that can be subclassed, but only within the same file where it is declared. This means that all subclasses of a sealed class must be defined in the same file as the sealed class itself. Sealed classes are useful for representing a restricted hierarchy of classes, where all possible subclasses are known in advance.
Sealed classes are useful in scenarios where you have a restricted set of possible values or states for a type, and you want to ensure that all possible values or states are accounted for in your code. By using a sealed class, you can define a finite set of subclasses that represent all possible values or states, and ensure that these subclasses are the only ones that can be instantiated.