Soda bread is a kind of soft, golden bread made with baking soda. In its most basic form, it contains only four ingredients: flour, salt, baking soda, and buttermilk.
Other ingredients can be added. For example, adding some sugar, raisins, and butter will make it a raisin soda bread.
Soda bread, or Irish brown bread, became prominent in 19th-century Ireland during the Great Famine (formerly called the "Irish potato famine"). It was dense and made of wheat, so it was cheap and filling. It truly became a lifeline during tough times.
Soda bread does not use yeast to get it to rise. Instead, the rise comes from baking soda reacting with the acid (soured milk or buttermilk). This makes it a 'quick' bread that can be made in under 15 minutes. The important thing to remember is to mix and knead the dough quickly and lightly. This will make a bread that is dense, but not doughy, with a tender, slightly moist interior.
Once the dough is formed into a round, a cross is cut on the top of the bread, which divides it into quarters called farls.