Salt (sodium chloride) is the only mineral 'rock' that is an essential part of the human diet. It is necessary for nerve transmission and muscle function. In everyday cooking, salt doesn't just make food salty; it is a flavor enhancer. It works by suppressing bitter flavors, which allows the sweetness and aromas of food to be more noticeable. This is why many people add a pinch of salt to chocolate or coffee. Historically, salt was so valuable it was used as currency; the word 'salary' comes from the Latin 'salarium,' which was money given to Roman soldiers to buy salt.