The job of the shutter is quite simple: it is to allow or stop light penetrating through to the film or digital sensor.
Unlike the sometimes-perceived complicated f-stop numbers of aperture, shutter speed is simply measured in fractions of a second.  Predominantly photos are taken between ranges of 1/60th (one-sixtieth) and 1/250th (one two-hundred-and-fiftieth) of a second.

Similar to the aperture setting the shutter speed has side-effects on the image apart from simply determining the correct amount of light being passed through to correctly expose the shot.

A photograph freezes a moment in time and varying our shutter speed can change how that moment in time is captured. Changing our shutter speed allows the photographer great creative input on the final image and allows interpretation on how this moment in time is captured.

The below shows the effects of aperture, shutter speed and ISO and the theoretical correct exposure for each.

Getting creative with the shutter

Adjusting our shutter speed allows great creative control and how our moment in time is going to be perceived.
You have seen the dreamy scenes of flowing water or the sports shots conveying a sense of movement and action, none of this would be possible without the creative use of shutter speed.

Mastering the shutter takes time and practise and with digital cameras it could not be easier, find yourself an interesting subject and experiment with shutter speeds.

What shutter speed to use really depends on how fast your subject is moving but as a rough guide a speed of 1/250th or faster will normally capture the action in crisp, sharp detail with no blurring.  At the other end of the scale long exposures of several seconds or more requires trial and error, before long you will develop a sense for how long a certain shot requires in a given a set of conditions.

How to convey movement

One of the harder messages to convey is the sense of movement, you are after enough blur to give the impression of action and movement without so much blur that it turns into a muddled, blurry mess. You can try settings in the range of 1/10th and 1/30th - you also have to remember that aperture comes into play to correctly expose the shot.

You can see now that just with these two core settings aperture and shutter speed there is an amazing scope of creativity to be had.

Photo credits

Intro photo by Hamad
Shutter speed examples by articnomad and kerri-jo