I think it's past time for another Stupid Questions thread, so here we go.
This thread is for asking any questions that might seem obvious, tangential, silly or what-have-you. Please respect people trying to fix any ignorance they might have, rather than mocking that ignorance.
Interviewers encourage interviewees to ask questions. And people holding presentations are asking for questions. Also people in general seem to like it if you ask questions about them. But not all of them. How do I choose good questions to ask in an interview, after a talk or with a person, especially when the interview answered all of my obvious question, as did the talk?