In my attempt to learn something new about photography, and aperture specifically, via the sapient and all-knowing Wikipedia, I have discovered some interesting things.
1. Though they are pertaining to the exact same thing, the aperture stop is not the "f-stop". We define and list the aperture according to f-stops, but the f-stop is not the actual aperture. Wow.
2. Some worthwhile terminology. In relation to focus, the aperture determines the cone-angle of a bundle of light rays, which in turn determines how collimated the rays are. Highly collimated rays will result in a sharpness of focus at the image plane, wheres as uncollimated result in sharpness of focus at specific focal length only. In summation, I learned what the aperture does in specific terms, in relation to focus.
3. Lastly, aperture refers to the diameter of the opening, not just the opening itself. Hmm...
b.m.