Ethanol, with more than 86 billion liters production in 2011, is the dominant biofuel in the global fuel market. Nowadays, ethanol is produced from starch- and sugar sources, so-called 1st generation ethanol, while lignocellulosic ethanol (2nd generation) is not yet applied for industrial applications. In general, the production includes pretreatment, eventual hydrolysis of sugar polymers by enzymes or acids, fermentation by baker’s yeast, for example, and downstream processes such as distillation, dehydration, and evaporation. Furthermore, the global production and consumption of ethanol has also raised ethical and social concerns about, for example, food vs. fuel. This chapter covers the details of processes for this biofuel production.