Wine is an alcoholic drink typically made from fermented grape juice. Yeast consumes the sugar in the grapes and converts it to ethanol, carbon dioxide, and heat. Different varieties of grapes and strains of yeasts produce different styles of wine. These variations result from the complex interactions between the grape's biochemical development, the reactions involved in fermentation, the grape's growing environment (terroir), and the production process. Many countries enact legal appellations intended to define styles and qualities of wine. These typically restrict the geographical origin and permitted varieties of grapes and other aspects of wine production. Wines not made from grapes involve fermentation of additional crops, including rice wine and various fruit wines such as plum, cherry, pomegranate, currant, and elderberry.