A dark ale with numerous variations, stouts are typically made with top-fermenting yeast. The common, dry variant of stout features a rich taste, frequently with chocolate or coffee notes. Like ales, stouts are brewed using warm fermentation, over 15 °C (59 °F). The natural fermentation processes cause the batch to foam at the surface, creating barm. This distinct feature caused beers obtained this way to be called top-fermenting.