Salt is an essential mineral for human life, and has been a valuable commodity since atiquity. Soldiers in ancient Rome, for example, were paid in salt. The term "salarium argentum" originally referred to the amount of salt paid to each soldier or citizen, but in time came to refer to allowances provided to buy the salt. This is the origin of the word "salary", which is still in use today. The Via Salaria (salt road) that was constructed to transport salt in ancient Rome still exists, and city names like Salzburg (salt town) in Austria continue to remind of just how important the salt trade once was.
The role of salt has changed significantly in recent times. Its use in food has been overwhelmingly surpassed by its use as a raw material for a wide variety of industrial products, particularly in the soda industry. Today, 80% of the salt produced in the world is used in industry. Japan is the world's foremost importer of salt, relying on imports to meet over 80% of demand. Global demand for salt continues to rise, driven mainly by China's economic growth. It is vital then, that we secure stable supplies of this precious resource.