TTL (Through The Lens) Metering is a method used in cameras to measure the amount of light reaching the camera sensor through the lens. This system allows the camera to automatically adjust settings like aperture, shutter speed, and ISO to achieve a well-exposed image. By analyzing the light that passes through the lens, the camera can accurately determine the correct exposure settings without requiring manual adjustments from the photographer. TTL metering is particularly useful in various lighting conditions, ensuring that the images captured are properly exposed.