Traditional (classical) biotechnology refers to techniques that have been used for thousands of years, such as fermentation processes. Key applications of fermentation included producing foods like beer, wine, cheese, bread and yogurt. These processes harness microbes like yeast and bacteria to convert sugars into products like ethanol, lactic acid, carbon dioxide and other compounds, allowing foods to be preserved and enhancing flavors. Traditional biotechnology built upon ancient techniques and helped enable major advances in food production and medicine.