Causing fermentation is the process of introducing yeast to a mixture of ingredients, such as sugar and water, in order to produce alcohol. The term 'YEASTY' is used to describe the process, which is also known as fermentation. Yeast is a single-celled organism that feeds on sugars and starches, producing carbon dioxide and alcohol as byproducts. This process is used to make beer, wine, and other alcoholic beverages.