How about some background into some of those terms we all use. I expect most photogs will know all about aperture, but for some of the people new to photography, it might help them to understand what all those f numbers mean.

Aperture

In optics, an aperture is a hole or an opening through which light travels.

via Aperture – Wikipedia, the free encyclopedia.

Aperture mechanism of Canon 50mm f/1.8 II lens