I have searched due on dictionaries. But I can't know what is the fundamental meaning of due. In my opinion, due means something is expected. But I am not sure whether it is really correct or not. Please, teach me this word.
The roots of this word can be traced all the way back to its Latin progenitor the verb debere which means to owe. So, if something is due, it means that it must be done because you're under obligation to do it.