Sourdough or sourdough bread is a bread made by the fermentation of dough using wild lactobacillaceae and yeast. Lactic acid from fermentation imparts a sour taste and improves keeping-qualities. Sourdough baking requires minimal equipment and simple ingredients – flour, salt, and water – but invites practice. Purism is a part of the appeal. As described by one enthusiast, "If you take flour, water, (wild) yeast and salt, and play around with time and temperature, what comes out of the oven is something utterly transformed."