I'll correct some misinformation provided above.
Fungi are not plants and do not derive energy from sunlight. Yeast is a cellular morphology that can be found in multiple fungal phyla including Basidiomycota (also includes mushrooms), Ascomycota and Zygomycota. It's generally believed that all fungi of these phyla can produce a yeast morphology under the right environmental conditions.
The most commonly encountered yeasts reproduce by budding but there are also fission yeasts that reproduce by dividing themselves in half with a central cross wall and then separating.
Saccharomyces spp. are most commonly used for alcohol and bread fermentations but the fission yeast Schizosaccharomyces pombe is used to make some african beers (pombe is swahili for beer).
Not all alcoholic beverages are fermented with yeasts or even fungi. Pulque (mescal. tequila) is a product of bacterial fermentation.