There are many types of alcohol, but the most common is ethyl alcohol, or ethanol. It is a clear, colorless liquid with a characteristic odor. It is used as a solvent, antiseptic, and fuel. Alcohol is produced by the fermentation of sugars and starches by yeast. It is also present in many fruits and vegetables. The alcohol content of a beverage is measured in proof, which is twice the percentage of alcohol by volume.