What is M2 in banking?

Could you please explain what M2 is in the context of banking? I'm a bit unfamiliar with the term and would appreciate a clear and concise explanation of its significance in the financial world. Is it a measure of the money supply, and if so, how does it differ from other measures like M1 or M3? Additionally, how does M2 factor into monetary policy decisions made by central banks, and how does it impact the overall economy? Thank you for your help in clarifying this important aspect of banking and finance.