Definitions for "Fill Flash"
Using the flash to lighten shadow areas or just to provide more overall illumination in situations where you normally wouldn't use the flash. Outdoors in bright light you get very stark shadows underneath of people's noses, chins and etc. Toggle the flash setting to "forced on" or "fill" and the flash will now fire on every shot. It also gives your human subjects that special little sparkle in their eyes.
The use of a flash to remove (or fill) shadows when there is otherwise enough light to take a picture, especially in strong sunlight.
Fixed Focus Flash Memory Focal Length