Shutter speed is the unit of measurement which determines how long shutter remains open as the picture is taken. The slower the shutter speed, the longer the exposure time. The shutter speed and aperture together control the total amount of light reaching the sensor. A short shutter speed will freeze things without much motion, so you can photograph fast movement. This is used mostly for car race shows and football matches. The longer the shutter speed, the more light gets into the camera. This would capture movement and the image would look blurred. This is useful to show movement or speed especially trying to show how busy your town is. Imagine your camera is like a window with shutters that opens and closes, aperture is the size of the window, if it's bigger more light gets through and the room will be brighter. The longer you leave the shutters open the more sun light that enters. Shutter speeds are expressed in seconds or fractions of a second.
Iman Khan