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. One instance is where the color of the light is an intrinsic part of the picture, like the warm colors of a sunset, or the cool blue light of an early dawn. If you’re shooting in a dimly-lit bar or restaurant, you might want to preserve the color of the ambient light rather than correct it. Another is where you want a consistent color balance across a series of pictures, and you don’t want the camera to be making its own automatic white balance adjustments from one shot to the next.
http://1.bp.blogspot.com/-BqVz3mW02WU/TljsgGtIGNI/AAAAAAAAAP4/Kz-EoGF81ZI/s1600/WhiteBalanceVariation.jpg
below are examples of photos taken with different white balance settings:
best photo
This is my best photo as the white balance has been set correctly to present the summery, bright theme of the flower with the warm, rich colours. The background is blurred out with a low aperture to make the subject stand out. The exposure has been set correctly so that the photo isn't bleached out or too dark. Finally, the colour of the red/pink flower stands out from the surroundings.
worst photo
This is my worst photo because it has not been focused correctly, resulting in the subject being blurry. Also, it is too zoomed in.