Sodium hydroxide (NaOH), also known as lye or caustic soda or sodium hydrate, is a caustic metallic base. Forming a strongly alkaline solution when dissolved in a solvent such as water, caustic soda is widely used in many industries, mostly as a strong chemical base in the manufacture of pulp and paper, textiles, drinking water, soaps and detergents. Worldwide production in 1998 was around 45 million tonnes. Sodium hydroxide is also the most common base used in chemical laboratories, and it is also widely used as a drain cleaner.