How is chlorine made?

Essentially, chlorine is made by passing an electric current through salt water (brine). There are three main production routes: the membrane, the mercury and the diaphragm process. Although most chlorine in Europe is now already manufactured using the membrane  process, the industry is committed to converting mercury production units to the more environmentally-sound membrane process by 2020.
Read more about the membrane, the mercury and the diaphragm process.