Way back when, shutter speed represented the length of time that film was exposed to light. Nowadays, it represents the amount of time a camera shutter stays open to expose itself to the image. It’s usually measured in fractions of seconds—the larger the denominator, the faster the speed. Anything lower than a 1/60 is difficult to use, and requires a tripod or some kind of image stabilization. When considering what shutter speeds to use in an image, it would be wise to first look to see if anything in the scene is moving and how you would like to capture that movement. You’ll have the option to freeze the shot or to create a blur. To freeze a movement, you’ll want a faster shutter speed. To create a blurry effect, you’ll want a slower shutter speed.
i.e.) 1/3000 is much faster than 1/30
1/30 of a second looks about natural for running water.
1/500 of a second freezes everything.
For sports use the fastest speed you can for most things unless you want deliberate blur.
Several full seconds will make waves look like a big, foggy blur.
(got that from here.)
Anything else you think is important to know about shutter speed?