Shutter Speed

Shutter speed is the amount of time light hits the camera sensor. There is a shutter in the camera that opens and closes when you take a picture. If the shutter speed is slow more light hits the sensor, thus causing blurriness and streaks of light. If the shutter speed is fast less light hits the sensor, which causes things to look still

Shutter speed allows light into the sensor as does aperture and ISO. The shutter speed determines how long the light is allowed to hit the sensor for. Aperture and ISO determine how much light hits the sensor.