Beer style beer differently. Since sugars are converted to alcohol during the process of fermentation, gravity can be used to estimate the final alcohol. In beer brewing, a distinction is made between the "original gravity", the gravity of the wort before fermentation has begun, and the "final gravity" of the product when fermentation has completed. Since the concentration of sugars is directly proportional to the gravity, the original gravity gives a brewer an idea of the potential alcoholic strength of the final product. After fermentation, the differences between the final and original gravities indicates the amount of sugar converted into alcohol, allowing
Low-alcohol beer commercial brewery, San Francisco's Anchor Brewing Company, also produces their "Anchor Small Beer" using the second runnings from their Old Foghorn Barleywine. The term is also used for commercially produced beers which are thought to taste too weak. The Middle East accounts for almost a third of worldwide sales of nonalcoholic and alcohol-free beer. Notable Islamic clerics in Saudi Arabia and Egypt have issued fatawa permitting the consumption of "alcohol-free" beers that can be proven to contain zero traces of alcohol. Alcohol-free beers such as Holsten, Barbican and Moussy are often available in stores and restaurants throughout the Arab world.