Shutter speed is what you want to change when you want to show movement in your picture or when you want to take an incredibly clear shot, a moment in time, without any blur of movement at all. The slower the shutter speed is, the more movement the camera will capture.
The three main adjustable parts of your camera are ISO, aperture, and shutter speed. Aperture and shutter speed together are what determines exposure because they both affect how much light is taken in while the picture is being taken. The most basic definition of shutter speed is how long the shutter takes to open and close.
Your camera’s shutter speed is measured in fractions of seconds. If you set your shutter speed to 1/1000 of a second it will be much faster than 1/10 of a second. Typically you won’t be using a shutter speed slower than 1/60 because any slower and you would include motion in your picture, making it blurry.
As you start exploring the different speeds you can use keep in mind, that you use a shutter speed slower than 1/60 you will need something to stabilize your camera, such as a tripod.
Also, there are some cameras now that have a built in image stabilization system to help your pictures not be effected by any accidental shakes.
If you are trying to take a picture with no movement you want to consider how close you are to the ‘action’ you are taking picture of. The closer you are to it the faster you want the shutter speed so that you won’t miss your shot. For example, if someone throws a ball right past your face you hardly see it but if you are a good distance off you see the ball the entire time.
When determining what you want your shutter speed to be, you have to know if you want to see movement in the finished picture or if you want a frozen moment to take with you. Just remember, the slower your setting, the more movement and motion you will see in your picture.