How do you calculate M2?

Could you please elaborate on the process of calculating M2? I understand that it's a monetary aggregate that includes currency in circulation, checking accounts, savings accounts, and other types of liquid assets, but I'm curious about the specific steps involved in determining its value. Is there a formula or methodology that is universally followed, or does it vary by country or region? And what factors influence the fluctuations in M2 over time? I'm eager to learn more about this important economic indicator.