Sodium hydroxide (NaOH), commonly known as lye or caustic soda, is a strong alkaline compound used in various industries. It appears as a white, solid substance and is highly soluble in water, producing heat during dissolution. NaOH is often used in the production of soap, paper, and detergents, as well as in water treatment processes. In addition to its industrial applications, sodium hydroxide is also utilized in laboratories for pH regulation and chemical synthesis. Due to its corrosive nature, it must be handled with care, as it can cause severe burns upon contact with skin or eyes.