Ethanol is a name for ethyl alcohol which is made by fermenting and distilling simple sugars.  Fuel ethanol must be rendered undrinkable by the addition of a denaturant (usually 2-5 percent gasoline by volume).

Fuel ethanol is often classified by its water content:
- Hydrous ethanol (typical of fuel ethanol produced for dedicated ethanol vehicles in Brazil) contains at least 5% water.
- Anhydrous ethanol (typical of fuel ethanol in the US) is manufactured using additional processing to further dehydrate the product to conform to ASTM (D4806) specifications which require a maximum water content of 1% by volume.