The functions of money include; (1)  medium of exchange,  (2)  store of value, and (3)  a calculate of worth.  Due to money is acceptable as a form of payment for all commodities, barter is no longer Required.  Money can be easily stored in a tin can or bank account, so commodities require not be stored and can be purchased when needed.  Because money is acceptable in virtually all transactions, prices can be stated in terms of dollars or yen thereby simplifying transactions substantially.  In other words, money is the grease that lubricates any difficult economic system