||Questions are usually identified with interrogative sentences or with what such sentences typically express. The exact definition of 'question' depends on the context in which they are the subject of study. Various phenomena are frequently associated with questions or even taken as characteristical for questions: question mark, interrogative pronoun/interrogative particle, rising intonation, inquisitive attitude, awareness of own ignorance, a goal to gain information. None of this is unanimously seen as characteristic of questions. The main issues of the works in this category concern (i) the nature of questions, (ii) the classification of questions, (iii) the role of questions in various walks of life (in philosophy, in anamnesis, in science, in criminal interrogation, etc.), and (iv) the relation of questions to knowledge and cognition.