Yeast belongs to the Fungi kingdom. Hundreds of different kinds of yeast are found around the world. Most live in the soil or on plants, especially in their fruit or nectar.
To reproduce, most types of yeast bud; a small section of a parent cell grows and breaks off to form a new cell. Reproduction through fission is common in a small number of yeasts. In this method, the parent cell separates itself equally into two cells.
Yeast is commonly used by beer and wine makers for fermentation, which results in the production of alcohol. Bakers use yeast for leavening, which causes dough to rise. However, some yeasts are harmful to humans. For instance, Candida albicans causes candidiasis, an infection that affects the skin, genitals, throat, mouth or blood.