To say the shutter, we must start with the imaging principle of the camera
All cameras can be reduced to small-hole imaging models. A small hole is opened in the closed paper box, and the light enters the box through the small hole, and the shutter is like, adding a lid to the small hole can control the light entering the paper box
Academic definition: The shutter is a device used in camera equipment to control the time when light illuminates the photosensitive element.