white balance refers to the process of neutralizing the color bias or tint in a digital image by adjusting the color of an intrinsic white in the image. Candidates include white signage, white clothing, or a white tablecloth.
When a video camera captures a scene it needs a reference as to what should be considered a natural white in that scene. This can be supplied as a manual white balance, or a white balance camera preset can be applied to match the color of the set lighting.
White balance can also be applied as a corrective post-production process, most effectively when working with raw, non-debayered formats like RED raw.