Caustic soda, also known as sodium hydroxide, is a powerful alkali widely used in industries and laboratories. In solid form, it appears as white flakes or pellets, and when dissolved in water, it releases a large amount of heat, making it a highly reactive substance. It is one of the most important industrial chemicals, with extensive use in the production of soaps, detergents, and cleaning products. In the textile industry, caustic soda is essential for cotton processing and fabric finishing. The paper industry uses it in pulping and bleaching processes, while the petroleum industry relies on it for removing acidic impurities from crude oil. Caustic soda is also valuable in water treatment, pH control, and food processing (such as peeling fruits and vegetables). Despite its versatility, sodium hydroxide is extremely caustic and can cause severe chemical burns upon contact with skin or eyes. It readily absorbs moisture and carbon dioxide from the air, so it must be stored in airtight containers. Due to its widespread applications and strong reactivity, caustic soda is considered a backbone chemical of modern manufacturing and industrial processes.