Alcohol is a colorless flammable liquid obtained by the fermentation of sugar and starch. It is used either in its pure or denatured form as a solvent in drugs, explosives, cleaning solutions or intoxicating beverages.

Alcohol is classified according to the relation between the carbon atoms in it. The most commonly used primary alcohols are methanol and ethanol. As methanol was formerly obtained from the distillation of wood, it is also known as wood alcohol. Methylated spirits or surgical spirits is a form of ethanol. Ethanol is used in the preparation of alcoholic beverages and as an industrial solvent. The simplest secondary alcohol is isopropanol, while butanol is a simple tertiary alcohol.

Alcohols are used in industries as reagents, solvents and fuels. The primary alcohols, methanol and ethanol, burn more efficiently than diesel or gasoline. Ethanol is used as a solvent in medical drugs and perfumes.

Alcohol can be made by fermenting fruits or grains with yeast. Ethanol is produced through fermentation in the production of fuel. Ethanol has been consumed by humans in the form of alcoholic beverages since prehistoric times. Consumption in large doses can cause acute respiratory failure or death and with chronic use has medical repercussions. About 20 percent of alcohol is absorbed by the stomach and 80 percent by the small intestine. The alcohol then enters the bloodstream and dissovles in the blood. The blood circulates the alcohol throughout the body, leading to intoxication.

The human body responds to alcohol in stages. Initially, a person comsuming alhocol experiences a state of euphoria, where he may become more self-confident and appear flushed. Later, he reaches a stage of excitement and is unable to react swiftly to natural situations. This is followed by a sense of stupor where he does not respond to stimuli. Excessive consumption of alcohol can lead to a coma or death.

Alcohol abuse and dependence causes emotional and social problems. This leads to marital and family problems, including domestic violence and work-related problems. While alcoholism has devastating effects on a person's health and social environment, there are medical and psychological ways to treat the problem.