A rhetorical question is a question that does not expect an answer and that is usually asked to make a point, insinuate something or for emphasis. Besides, the answer to this type of question is usually obvious. <em>Is grass green?</em> is a perfect example of a rhetorical question because its answer is too obvious (<em>Of course the grass is green!</em>) and thus, it does not expect a direct answer. Depending on the context, this question can be asked to make a point on a topic or insinuate something.