I'm an amateur in type and I once read what the idea is behind the 'medium' weight, but now I forgot.
So what I'd like to learn is:
(1)What's the purpose of the medium weight, sitting between standard and semi-bold? What do people generally use it for?
(2)I want to set a letter in Minion Pro. Should I use the standard or the medium weight, or can I opt for either one?