Although the benefits and risks associated with moderate drinking have gained increasing attention in recent years from both researchers and the general public, no universal definition of moderate drinking exists. Most currently used definitions are based on a certain number of drinks consumed in a specific time period. Defining a "drink," however, also is difficult because alcoholic beverages can differ substantially in their alcohol content, even within the same beverage category (e.g., beer, wine, or distilled spirits). Because international differences in drink definitions also exist, comparing studies from different countries is difficult. The development of a universal definition of moderate drinking is hampered further by variations in the way alcohol consumption levels and drinking patterns are being assessed (i.e., the survey methods and assessment modes used). Despite these problems, definitions of moderate drinking and drinking guidelines have been developed in the United States and other countries.