Acids are chemical substances that have a sour taste and are present in both organic materials like plants and animals as well as being prepared from minerals in the earth. Mineral acids include hydrochloric acid, sulfuric acid, and nitric acid, though carbonic acid is also considered a mineral acid but is weak. Bases are chemical substances with a bitter taste that change red litmus to blue and are the chemical opposites of acids, being able to neutralize acids.