This document discusses the key features and functions of a camera. It begins by defining a camera as an optical instrument used to take photographs or make films. It then explains the primary features that control a camera's functionality - focus, aperture, shutter speed, and ISO. Focus controls the sharpness of the image by adjusting the lens. Aperture regulates the size of the lens opening to control the amount of incoming light. Shutter speed determines how long the camera's shutter remains open during an exposure. And ISO specifies the light sensitivity of the image sensor, with higher ISO resulting in lower image quality.