Shutter speed
Shutter speed is just a little thing that lets in light most camera range from 1/4000s to 30seconds.
Shorter shutter speeds are for freeze framing an image. Long shutter speeds lets in light and creates motion blur.
 In a good day light you should use around 1/125 or 1/250 of a second. The lowest shutter speed that doesnt create motion blur is 1/60s.
Anything lower than 1/60 you should use a tripod. 

Here are some images that i created using different shutter speeds.

 to get this effect i used a shutter speed of 1/125 to capture the motion of her

running.