During alcoholic fermentation, yeast and a few other microorganisms undergo alcoholic fermentation which produces ethyl alcohol and carbon dioxide.

Use this link and click on the button that says alcoholic fermentation to watch a short animation of the process.

The diagram below shows a visual summary of alcoholic fermentation.

Alcoholic fermentation is the process that causes bread dough to rise. When yeast cells in the dough run out of oxygen, the dough begins to ferment, giving off tiny bubbles of carbon dioxide. These bubbles are the air spaces you see in a slice of bread. The small amount of ethyl alcohol that is produced in the dough evaporates when the bread is baked.

Watch this time lapse video to see alcoholic fermentation in action.