Alcohols are a class of compound that are derived from hydrocarbons that have extra hydroxyl (OH) groups attached to them. By far the most commonly known is ethyl alcohol, but there are many others (eg. methanol, glycerol) that occur naturally in the body and can be compounded synthetically.
Ethyl alcohol (C2H5OH) or ethanol, is a colourless, liquid, organic compound produced by fermentation of carbohydrates (sugars) in fruit (eg. grapes) or grain (eg. wheat). Less commonly, it may be produced by fermenting vegetables, or even milk and honey. It produces immediate effects on the human body as it is absorbed from the stomach rather than the intestine, reaching a maximum level 90 minutes after ingestion, then slowly dissipates and is broken down by the liver and excreted through the kidneys at a fixed rate over the next 12 to 15 hours.
Alcohol is normally consumed in the form of intoxicated liquids that have varying strengths of alcohol. The alcohol in beer varies from below 2% alcohol to over 8%. Wines vary from about 8% to over 14%, while fortified wines (eg. sherry, port) vary from 18% to 22% alcohol. Spirits (eg. gin, whisky, brandy, rum) and liqueurs usually contain 40% to 50% alcohol, but some overproof spirits go much higher.