White balance is a camera setting that adjusts the color balance of light the you’re shooting in so that it appears a neutral white, and it’s used to counteract the orange/yellow color of artificial light, for example, or the cold light of deep shadow under a blue sky so that portrait shots taken in shade look more natural.
All digital cameras have an auto white balance setting that analyses the colors in a scene and neutralises them automatically. Mostly it does a very good job, though there are occasions when you need to override the auto white balance setting and choose a setting yourself.
White balance effects the colour of the picture depending on what lighting you are in.
In most cases, though, accurate color rendition is going to call for a manual white balance setting. Those settings choices are incandescent, fluorescent, flash, cloudy, open shade, sunny, Kelvin color temperature and PRE. The Incandescent setting is best for traditional household bulbs; Fluorescent will prevent the green cast common to photos taken in fluorescent light; Cloudy will add a bit of warmth to the light; Flash adds a more aggressive touch of warmth to take the edge off the bright light of a flash; Open Shade adds a slight pink tone to eliminate the blue cast that shadows take on in open shade; and Sunny sets the color temperature to 5000 degrees Kelvin, which is typical of mid-day sun.