A shutter is a mechanical or electronic system in a camera that controls the duration of time light is allowed to reach the film or digital sensor. By regulating exposure time, the shutter determines how motion, brightness, and image sharpness are captured.
Shutters come in various types, including focal-plane shutters commonly found in SLR cameras and leaf shutters often used in medium- and large-format lenses. Mastering shutter use is essential for photographers to control motion blur, freeze action, and achieve correct exposure across different lighting conditions.