Aperture, Shutter Speed and ISO - what are they?

f2.8

f16

1. The pupil
2. Finish this sentence - the smaller the Aperture _The less light that is let in_, the higher the Aperture _the more light that is let in_. 
3. Aperture changes the depth of field by sharpening a part of the image and blurring out the other.
   Slow Shutter Speed
   
   
   Fast Shutter Speed

In the first scenario, I would use Fast Shutter Speed.

In the second scenario, I would use Slow shutter Speed.

Auto, Shutter Priority, Manual

ISO 200

ISO 3200

1. To get Ultra Fast Shots
2. you should always try to stick to the lowest ISO (base ISO) of your camera, which is typically ISO 100 or 200, whenever possible. When there is plenty of light, you should always use the lowest ISO, to retain the most detail and to have the highest image quality.
3. You should increase the ISO when there is not enough light for the camera to be able to quickly capture an image.