White bread typically refers to breads made from wheat flour
from which the bran and the germ layers have been removed (and set aside) from the whole wheatberry as part of the flour grinding or milling process, producing a light colored flour. This milling process can give white flour a longer shelf life by removing the natural oils from the whole grain. Removing the oil allows products made with the flour, like white bread, to be stored for longer periods of time avoiding potential rancidity.
The flour used in white breads may be bleached, that is lightened further, by the use of chemicals such as potassium bromate, azodicarbonamide, or chlorine dioxide gas to remove any slight, natural yellow shade and make its baking properties more predictable. Some flour bleaching agents are banned from use in some countries.