How the Fed defines the money supply:

M-1: Currency held by the public, including coin; traveler's checks; balances in checking, NOW, and super-NOW accounts; balances in accounts with Automatic Transfer Service; balances in credit union share accounts.

M-2: M-1, plus savings and small time deposits (less than $100,000), including money market deposit accounts; overnight repurchase agreements at commercial banks; certain Eurodollar deposits; shares in money market mutual funds held primarily by households and small businesses.

M-3: M-2, plus large time deposits ($100,000 or more); repurchase agreements with maturities longer than one day at commercial banks and savings-and-loan associations; shares in money market mutual funds which are used by large financial institutions and corporations.