Aperture. What are they?

F16 setting is smaller but bigger.

F2.8 setting is bigger but smaller.

1. A part of the body that can be mostly related w/ aperture, would be the pupil. The reason for that is b/c it depends on the amount of light pass through that lens just like an eye.
2. The smaller the aperture the higher, The higher the aperture the smaller.
3. Depth of field is basically how sharp the image is. Kind of how sharp the pic is and even though you can still see the background, it's blurred out.