Yeast
In short
Yeast is a tiny, single-celled organism that belongs to the fungus family. It is most commonly used in cooking to make bread rise and to create alcoholic drinks.
In plain words
Yeast is a living thing that is too small to see without a microscope. When yeast eats sugar, it breathes out carbon dioxide gas and produces alcohol. In baking, the gas gets trapped in the dough, creating little bubbles that make the bread light and fluffy. In brewing, the alcohol is kept to make drinks like beer.
A simple example
When you make a loaf of bread, you mix yeast with flour, water, and sugar. As the yeast eats the sugar, it releases gas that puffs up the dough like a balloon. Once you bake it in the oven, the bread stays big and soft instead of being a hard brick.
Why it matters
Yeast is essential for the food industry. Without it, we would not have fluffy bread, pastries, or many popular fermented drinks. It is also used in science and medicine to help researchers study how living cells work.
Easy to mix up
People often mix up yeast with baking powder. While both make things rise, baking powder uses a chemical reaction to create bubbles instantly, whereas yeast is a living organism that needs time to eat and grow.