Salt (sodium chloride) is the only rock that humans regularly eat. It is essential for life, as sodium and chloride ions are required for nerve and muscle function and to maintain fluid balance. 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. In cooking, salt is not just a flavor; it is a flavor enhancer. It works by suppressing bitterness, which allows the sweetness and aromas of food to shine through. It also alters the physical structure of proteins, which is why salting meat before cooking makes it more tender and juicy.