M0: The total of all physical currency including coinage. M0 = Federal Reserve Notes + US Notes + Coins. It is not relevant whether the currency is held inside or outside of the private banking system as reserves.
MB: The total of all physical currency plus Federal Reserve Deposits (special deposits that only banks can have at the Fed). MB = Coins + US Notes + Federal Reserve Notes + Federal Reserve Deposits
M1: The total amount of M0 (cash/coin) outside of the private banking system plus the amount of demand deposits, travelers checks and other checkable deposits
M2: M1 + most savings accounts, money market accounts, retail money market mutual funds, and small denomination time deposits (certificates of deposit of under $100,000).
MZM: 'Money Zero Maturity' is one of the most popular aggregates in use by the Fed because its velocity has historically been the most accurate predictor of inflation. It is M2 – time deposits + money market funds
M3: M2 + all other CDs (large time deposits, institutional money market mutual fund balances), deposits of eurodollars and repurchase agreements.
M4-: M3 + Commercial Paper
M4: M4- + T-Bills (or M3 + Commercial Paper + T-Bills)
L: The broadest measure of liquidity that the Federal Reserve no longer tracks. Pretty much M4 + Bankers' Acceptance