Exposure Composition
Exposure Composition is usually done automatically by your camera using its light metering system. The camera measures the incoming light and adjusts the aperture, and shutter speed, to give you pictures with the correct exposure.
Most digital cameras will adjust the aperture first; once it can no longer adjust the aperture to get the correct exposure it will then adjust the shutter speed.
If your camera can be adjusted manually you can use a light meter and set your own exposure and white balance to get the effects that you want.
Color is on a spectrum. The white balance setting tells your camera what objects in your frame is white then the camera itself will fill in the spectrum. The spectrum is determined by the temperature of the light that is given off of each color.
References
Photoxel.com
Wikipedia.com
PHOTO OF THE DAY
HEN EGG MOUNTAIN; Terlingua, TX
Olympus E-500
Zoom lens set at 150
Auto Landscape setting
UV filter