Frontlights are thin panels used to illuminate LCDs from above. They are currently available for the Game Boy Color and Game Boy Advance. Small micro laser dots disperse light from LEDs located on the bottom of the panel allowing for game illumination underneath. Some LCDs cannot be backlit such as the Game Boy Color and Game Boy Advance; these consoles need to be lit from the front, hence front light.
LOCA ( Liquid Optically Clear Adhesive) is a term often heard when speaking about frontlights. It is a special glue that allows for better light dispersion and clarity when installing a frontlight modification. It is highly recommended for all frontlight mods.