Alcoholic drink which contains a very high level of alcohol and "does not contain any added flavoring" is commonly called a neutral spirit. Generally, any distilled alcoholic beverage of 170 US proof or higher is considered to be a neutral spirit. Most yeasts cannot reproduce when the concentration of alcohol is higher than about 18%, so that is the practical limit for the strength of fermented drinks such as wine, beer, and sake. However, some strains of yeast have been developed that can reproduce in solutions of up to 25% ABV. Shot sizes vary significantly from country to country. In the United
Alcoholic drink of fortified wine have been developed, including port, sherry, madeira, marsala, commandaria, and the aromatized wine vermouth. Rectified spirit, also called "neutral grain spirit", is alcohol which has been purified by means of "rectification" (i.e. repeated distillation). The term "neutral" refers to the spirit's lack of the flavor that would have been present if the mash ingredients had been distilled to a lower level of alcoholic purity. Rectified spirit also lacks any flavoring added to it after distillation (as is done, for example, with gin). Other kinds of spirits, such as whiskey, are distilled to a lower alcohol percentage to