Fill flash is a photography technique where a photographer uses flash in combination with natural light to add light to the subject of a photo. It is typically used in situations where there is strong backlighting, such as when the sun is behind the subject. The fill flash helps to reduce the contrast between the bright background and the darker subject, resulting in a more balanced exposure. Fill flash is particularly useful in portrait photography, where it can help to eliminate harsh shadows and create a more flattering image of the subject. It is also useful in outdoor photography, where it can help to add detail and texture to the subject, particularly if the subject is backlit by the sun. When using fill flash, it is important to balance the intensity of the flash with the available natural light. Too much flash can result in an overexposed and artificial-looking image, while too little flash may not provide enough light to balance the exposure. Skilled photographers often experiment with different flash settings to achieve the desired effect.