Caustic soda, also known as sodium hydroxide (NaOH), is a strong inorganic base commonly used in various industrial and chemical processes. It is a white, hygroscopic solid that is highly corrosive and can cause severe burns on contact with skin and eyes.

Caustic soda is produced by the electrolysis of aqueous sodium chloride, also known as brine, which is a solution of water and salt.

In the chemical industry, caustic soda is used in the production of soaps, detergents, and other cleaning products, as well as in the production of other chemicals such as rayon, cellophane, and bisphenol A.

In the oil and gas industry, caustic soda can be used as a pH adjusting agent in drilling fluids. The pH of a drilling fluid is an important parameter that must be controlled to maintain the stability of the fluid and prevent damage to the borehole and formation.

In the pulp and paper industry, caustic soda is used to break down wood fibers and remove lignin, the natural adhesive that holds the wood fibers together, to produce pulp.

In the metal industry, caustic soda is used in the cleaning and pickling of metal surfaces, as well as in the production of aluminum.

In the food industry, small amount of caustic soda is used as a pH adjuster, leavening agent and in food processing.