The shutter speed of your camera is the measure of how long the shutter remains open to expose the sensor. Any motion that occurs while the shutter is open will show on the image. (the faster the shutter speed the more likely you are to freeze the movement). Shutter speeds are based on the doubling or halving of seconds. The following is a general list of the most common shutter speeds from long to short: 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000, 1/2000, 1/4000, 1/8000. As you can imagine the 1/8000 of a second shutter speed would just about freeze any movement. The shutter speed for Image 1 below is 1/20th of a second. This by no means freezes the movement but you can see that much of the movement was stopped. The shutter speed for Image 2 was 1.1 seconds allowing the movement to blur the image. Really it depends on what type of image you are going for. If you have any questions please feel free to contact me.
Shutter Speed: 1/20 sec
Shutter Speed: 1.1 sec