In which class is it better to implement the storage of the current state in object-oriented programming?

Storing the current state of an object is best implemented within the class that describes this object. This aligns with the principles of encapsulation in OOP: the state (fields) and behavior (methods) are combined in a single class. If the state is complex or requires separate management, a separate state class can be created and the "State" pattern can be used, but in simple cases, the state is stored as private fields within the class.