What is money and what functions does it serve?

"Money is anything that is acceptable as payment for goods and services. For money to be a suitable means of exchange, it should be scarce, durable, portable, and divisible. Money functions as a medium of exchange, a standard of value, and a store of value. The U.S. money supply consists of currency, demand deposits, and time deposits. Currency is cash held in the form of coins and paper money. Demand deposits are money kept in checking accounts that can be withdrawn by depositors on demand. Time deposits are deposits at a bank or other financial institution that pay interest but cannot be withdrawn on demand. M1 includes currency and demand deposits. M2 includes all M1 monies plus time deposits and other money that is not immediately accessible."