Caustic fluids, also known as lyes, are highly corrosive liquids that can cause severe burns and tissue damage. They are typically composed of strong acids or bases, such as sodium hydroxide or sulfuric acid, and are used in a variety of industrial and household applications. Caustic fluids are often used to clean surfaces, remove stains, and dissolve organic materials. In addition, they are used in the production of soaps, detergents, and other cleaning products.