Ammonium chloride is a white crystalline salt with the chemical formula NH₄Cl, known for its high solubility in water and mildly acidic properties. It is formed by the reaction of ammonia (NH₃) and hydrochloric acid (HCl) and is commonly found as a byproduct in various industrial processes, such as the Solvay process for soda ash production. Ammonium chloride has a salty taste and sublimates upon heating, making it useful in a range of applications. It is non-flammable and relatively stable under normal conditions, though it should be stored in a cool, dry place to prevent moisture absorption.