Sourdough bread is a type of bread made from a dough that has been fermented with a sourdough starter. The starter is a mixture of flour and water that contains naturally occurring yeast and bacteria. The fermentation process gives the bread a slightly sour flavor and a dense, chewy texture.

To make sourdough bread, the starter is mixed with flour, water, and salt to create a dough. The dough is then allowed to rise for several hours, or even overnight, before being shaped and baked. The long fermentation time allows the bread to develop a complex flavor and texture.

Sourdough bread is popular in many cultures and is often associated with artisanal and traditional bread making. It is also considered to be healthier than other types of bread, as the fermentation process breaks down some of the gluten and makes the bread easier to digest.