Lactose is a non-fermentable milk sugar that is perhaps best known to brewers as the source of sweetness in sweet stouts, such as milk stout or cream stout. It can be used in varying amounts to give different levels of sweetness to beer, and may be included in recipes where more sweetness is desired. Because it is a non-fermentable sugar, it can also be used to add sweetness back to ciders that have fermented to dryness.