What are the measures of money supply?

The RBI uses four measures of money supply denoted as $M_1,M_2,M_3,M_4.$

$M_1$ = Currency notes and coins in circulation with public (but not those held by banks) + Net demand deposits with the commercial banks + Other deposits

$M_2$ = $M_1$ + Deposits with post-office savings banks

$M_3$ = $M_1$ + Fixed deposits with banks

$M_4$ = $M_3$ + All post-office savings bank deposits

In India, $M_3$ is the most commonly used measure of money supply.