Oranges are round citrus fruits ranging in diameter from about 2 to 3 inches, with finely texturized skins that are, of course, orange in color, just like their pulpy flesh. They are undoubtedly one of the most popular fruits in the world. Oranges are classified into two general categories sweet and bitter with the former being most commonly consumed. Popular varieties of the sweet orange (Citrus sinensis) include Valencia, Navel, and Jaffa oranges, as well as the blood orange, a hybrid species that is smaller in size, more aromatic in flavor, and has red hues running throughout its flesh. Bitter oranges (Citrus aurantium) are used to make jam or marmalade, and their zest serves as the flavoring for liqueurs such as Grand Marnier and Cointreau.