1. Aperture
It’s the function that lets you control how much light enters the camera.

2. Aperture Priority Mode (A or AV)
Light passes through your camera lens through a hole. This hole decides how much light to let onto your camera sensor. Aperture is the size of that hole inside the lens.

4. Aperture Priority Mode
Just like how your pupils react to light. If you shine a light in your eyes your pupils will get smaller, but in a darker room they will dilate to try and let as much light in as possible.

5. Aperture Priority Mode (A or AV)
You choose the aperture and your camera chooses the other settings to ensure you have a well balanced exposure.
You may need a tripod depending on the shutter speed that the camera chooses for you.
Aperture is measured in F-numbers. This is the measurement of the diameter of the hole. 
Aperture is referred to as
F-stops.

6. Aperture Priority Mode (A or AV)
If you look at a lens you will see it has an F-stop range or number.
The most common F-stops are: ƒ/

7. Depth of Field
Depth of field is the amount of distance between the nearest and farthest objects that appear in focus in a photograph.

8. Aperture Priority Mode (A or AV)
AV is useful when you’re looking to control the depth of field in a shot (usually a non moving object).
LARGE aperture number =
smaller aperture (small opening)
less light in
LARGER depth of field (more in focus).
Small aperture numbers mean the opposite

9. Lots of Blur
All Sharp