Instead chemicals should be stored according to their reactivity and other properties. For example, acids and bases are incompatible and should be stored separately, whereas sodium and potassium can be kept together as they are both water-reactive but do not have any added hazard when placed with one another.[2] The United Nations Globally Harmonized System of Classification and Labeling of Chemicals (GHS) is an international system created by the United Nations to classify chemicals.[3] The Safety Data Sheet (SDS) or Material Safety Data sheet (MSDS) identifies and classifies the properties and hazards of chemicals.[3]