Yeast is a tiny living organism that belongs to the fungus kingdom. It plays a crucial role in baking and brewing, as it helps dough rise and ferments sugars to produce alcohol. When yeast consumes sugar, it releases carbon dioxide and alcohol, which gives bread its fluffy texture and beer its bubbly fizz. There are many types of yeast, but the most common one used in baking is Saccharomyces cerevisiae. This friendly microorganism is not only essential for making delicious foods and drinks but also contributes to the production of vitamins and nutrients, making it beneficial for our health.