The shutter speed is the unit of measurement which determines how long shutter remains open as the picture is taken. The slower the shutter speed, the longer the exposure time. The shutter speed and aperture together control the total amount of light reaching the sensor. www.webopedia.com/TERM/S/shutter_speed.html
My examples using fast shutter speed range from 1/4000 - 1/160:
Best and Worst:
BEST
This is my best image because you can see the water droplets clearly as it was taken on a high shutter speed setting.
WORST
This is my worst image because it is very blurry so the water can't be seen clearly, this is because it was taken on a slow shutter speed setting.