shutter speed:
Shutter speed is the amount of light when the shutter is open so basically how much light is allowed in the picture. Shutter speed is measured in seconds. To let a lot of light in it your numbers will be around 1/10. To let no light in it will be 1/4000. For example if you taking a picture of people running you shutter speed should be around 1/2000 and if you're taking a picture of something still it could be 1/200. This will make a big difference to your picture because it won't be as blurry and dark.
This image shows a fast shutter speed. it shows a sharp picture and was taken around 1/3000 shutter speed. The diagram shows what speed you need it on depending on the persons speed.These are pictures showing a fast shutter speed. This is because we are getting the person in action.