Alcohols are a family of organic compounds containing one or more hydroxyl functional groups (-OH). The general formula for an alcohol is R-OH. R represents a hydrocarbon.

Alcohols can be produced by chemical synthesis, or, as is the case in ethanol production, by fermentation.

Alcohols can contain one or more hydroxyl groups.

For example, ethanol contains a single hydroxyl group. It is an important organic compound with many industrial/technological applications. For example, ethanol is added to gasoline to increase the fuel's octane number.

Alcohols that contain a single hydroxyl functional group can be classified as primary, secondary, or tertiary depending on the position of the hydroxyl group and the bonding of the structure.

• Primary alcohols - The hydroxyl group is attached to a terminal carbon.
  
• Secondary alcohols - The hydroxyl group is attached to a carbon that is bonded to two other carbon atoms.
  
• Tertiary alcohols - The hydroxyl group is bonded to a carbon atom that is bonded to three other carbon atoms.
  

Some alcohols contain more than one -OH group and are referred to as polyalcohols. For example, ethylene glycol (found in antifreeze) is a polyalcohol.