The function of a sensor in a digital camera is to capture light and convert it into an electronic signal. The sensor is the part of the camera that replaces the role of film in traditional cameras. When the shutter button is pressed, the sensor in the camera detects and records the light that enters through the camera lens. It converts the light into digital information in the form of pixels, which are then processed by the camera's image processor to create the final photograph. The sensor's quality, resolution, and sensitivity to light are crucial factors in determining the image quality and overall performance of a digital camera.