In photography, shutter speed or exposure time is the length of time when the film or digital sensor inside the camera is exposed to light, also when a camera’s shutter is open when taking a photograph. The amount of light that reaches the film or image sensor is proportional to the exposure time. 1/500 of a second will let half as much light in as 1/250.
Shutter speed is the length of time of the camera shutter is open, allowing light to enter onto the sensor. Alternatively, it is the time of your camera spends taking a photo.