If your iPhone's automatic settings make a shot too bright or too dark, what specific control allows you to quickly make it a little brighter or darker without changing the shutter speed or ISO?

The specific control on an iPhone that allows you to quickly adjust the brightness without directly changing the shutter speed or ISO is the Exposure Compensation slider, often referred to as the Brightness slider. When you open the Camera app, tapping anywhere on the screen will set the focus and the initial automatic exposure for that point. A yellow square will appear indicating the focus area. Adjacent to this square, a small sun icon with a vertical slider will become visible. Dragging this slider upwards, towards the sun icon, will make the shot brighter, while dragging it downwards will make the shot darker. This slider directly controls the exposure compensation, which is a manual adjustment you apply to the camera's automatically determined exposure. Essentially, you are telling the camera to intentionally overexpose (make brighter) or underexpose (make darker) the image. While the iPhone's internal system will then automatically adjust parameters such as the shutter speed, ISO, or both, to achieve the requested exposure compensation, the user is not directly selecting or manipulating those specific settings. The control simplifies the process by allowing you to intuitively set the desired brightness level without needing to understand or manage the underlying technical exposure components like shutter speed or ISO.