READ: Shutter Speed

Summing it up

So you should know a bit about shutter speed now!

Moral of the story:

Fast shutter = use when you have tons of light and don't need light to rush into the camera for as long as possible. Use to shoot things that are going fast to get them in focus.

Slow shutter = use when you don't have lots of light. Keep the camera still so that things moving won't be blurry.