Question

what is Open Market Operation ?

Answer 1

An open market operation is an activity by a central bank to give liquidity in its currency to a bank or a group of banks. 

Answer 2

An open market operation (OMO) is an activity by a central bank to give (or take) liquidity in its currency to (or from) a bank or a group of banks. The central bank can either buy or sell government bonds in the open market (this is where the name was historically derived from) or, in what is now mostly the preferred solution, enter into a repoor secured lending transaction with a commercial bank.