Coins are a form of legal tender first used c. 6th century BCE in India. The need arose for a stable mode of payment and coins have risen gloriously to the occasion. Previous methods of payment have been replaced over time. But what has enabled coins to be used for payment for over two millennia? The stability in the value of precious metals can only go so far. But when combined with the authentication done by governing authorities, coins become a stable and reliable form of money.