Japanese rice wine is an alcoholic beverage made by fermenting rice that has been polished to remove the bran. Despite the name Japanese rice wine, sake, and indeed any East Asian rice wine (such as huangjiu and cheongju), is produced by a brewing process more akin to that of beer, where starch is converted into sugars which ferment into alcohol, whereas in wine, alcohol is produced by fermenting sugar that is naturally present in fruit, typically grapes.
The brewing process for sake differs from the process for beer, where the conversion from starch to sugar and then from sugar to alcohol occurs in two distinct steps. Like other rice wines, when sake is brewed, these conversions occur simultaneously. The alcohol content differs between sake, wine, and beer; while most beer contains 3–9% ABV, wine generally contains 9–16% ABV, and undiluted sake contains 18–20% ABV (although this is often lowered to about 15% by diluting with water prior to bottling).
In Japan, where it is the national beverage, sake is often served with special ceremony, where it is gently warmed in a small earthenware or porcelain bottle and sipped from a small porcelain cup called a sakazuki. As with wine, the recommended serving temperature of sake varies greatly by type.