lighting.

Ambient Light	The light already present in a scene, before any additional lighting is added. More info: Ambient Light
Incident Light	Light seen directly from a light source (lamp, sun, etc).
Reflected Light	Light seen after having bounced off a surface.
Colour Temperature	A standard of measuring the characteristics of light, measured in kelvins. More Info: Colour Temperature Chart
Contrast Ratio	The difference in brightness between the brightest white and the darkest black within an image. More Info: Contrast Ratio
Key Light	The main light on the subject, providing most of the illumination and contrast.More Info: 3 Point Lighting The image below shows this: Below shows Key light with less glare (created when the camera is too close to a light) :
Fill Light	A light placed to the side of the subject to fill out shadows and balance the key light. More Info: 3 Point Lighting
Back Light	A light placed at the rear of a subject to light from behind. More Info: 3 Point Lighting The image below shows both key light and back light used. Notice the 'halo' effect above the sholder:
Hard Light	Light directly from a source such as the sun, traveling undisturbed onto the subject being lit.
Soft Light	Light which appears to "wrap around" the subject to some degree. Produces less shadows or softer shadows.
Spot	A controlled, narrowly-focused beam of light.
Flood	A broad beam of light, less directional and intense than a spot.
Tungsten	Light from an ordinary light bulb containing a thin coiled tungsten wire that becomes incandescent (emits light) when an electric current is passed along it. Tungsten colour temperature is around 2800K to 3400K. Also known as incandescent light.
Halogen	Type of lamp in which a tungsten filament is sealed in a clear capsule filled with a halogen gas.
Fresnel	A light which has a lens with raised circular ridges on its outer surface. The fresnel lens is used to focus the light beam.
Incandescent	Incandescent lamps produce heat by heating a wire filament until it glows. The glow is caused by the filament's resistance to the current and is called incandescence