Baking soda is a leavening agent that is commonly used in recipes that mix moisture plus an acidic ingredient together to make batter rise. In the UK, baking soda is known as bicarbonate of soda. Bicarbonate of soda is alkaline and can leave a tangy flavor if overused, so it should be sifted very well. Bicarbonate of soda is also used as a cleaning agent and can be used to clean dirty mattresses, polish tarnished jewelry, and even get the kitchen sink sparkling. Baking powder is different from baking soda/bicarbonate of soda as it is pre-mixed with a dry acidic ingredient that causes baking to rise when mixed with wet ingredients. Baking powder is often used in more delicate tasting bakes as it has a relatively undetectable taste. Baking powder is usually found in recipes that do not include an acidic ingredient. In the UK, bicarbonate of soda can be bought in almost all supermarkets and is usually kept near or in the baking aisle.