Typically, we recognize acids and bases by their simple properties, such as taste. We know that a lemon is sour, so it is acidic. Bases tend to taste bitter. Acids and bases also change the color of certain dyes, such as phenolphthalein and litmus. Acids change litmus treated paper from blue to red. Acids change basic phenolpthalein from red to colorless. Bases change litmus treated paper from from red to blue and phenolphthalein from colorless to pink. Acids and bases neutralize the action of each other. This is why we take antacids for stomachaches, because the antacid is a base, and neutralizes the acid in the stomach. This section will teach you all you need to know about Acids & Bases.