The chemical substance hydrochloric acid is the aqueous (water-based) solution of hydrogen chloride (HCl) gas. It is a strong acid, the major component of gastric acid and of wide industrial use. As a highly corrosive liquid, hydrochloric acid should be handled only with appropriate safety precautions.
Hydrochloric acid, or muriatic acid by its historical but still occasionally used name, has been an important and frequently used chemical from early history, and was discovered by the alchemist Jābir ibn Hayyān around 800. It was used throughout the Middle Ages by alchemists in the quest for the philosopher's stone, and later by several European scientists including Glauber, Priestley, and Davy, to help establish modern chemical knowledge.
During the Industrial Revolution, it became an important industrial chemical for many applications, including the large scale production of organic compounds such as vinyl chloride for PVC plastic and MDI/TDI for polyurethane and smaller scale applications, such as production of gelatin and other ingredients in food, and leather processing. Currently, production is approximately 20 million metric tonnes annually (20 Mt/year) of HCl gas.