Yeast is present in so many things that we consume, but many of us don’t know what it really is. It can be confusing to try to understand what this magical substance that makes dough double its size is, so we’re going to make it simple. Yeast is a type of bacteria called Saccharomyces cerevisiae. It is a single-cell bacteria that converts sugars and scratches into carbon dioxide and alcohol. It does this through a process called fermentation. When involved in baking, it is the carbon dioxide produced that makes the dough rise. Yeast can be bought in a few forms, such as fresh, instant dry, and active dry. All yield the same results but have different shelf lives and shapes. Yeast is grown in factories and then combined with molasses, which is how it transforms into its buyable form. It can also be made at home or in nature. For example, making sourdough starter at home is a type of yeast. Now that you know what yeast is, you can be more informed the next time you use it!