This article explains how to create an ATM System Sequence Diagram, and how it can be used to understand financial flows. Through this visual representation of the banking process, users can easily identify any errors or out-of-sequence steps and take corrective action. The diagram also reveals how each step, including authorization, card entry, transaction methodology and communication protocols, interact with each other. Understanding this ATM System Sequence Diagram gives users a clearer understanding of banking processes, from top to bottom. With this improved understanding of financial flows, banks can optimize resources for more effective and efficient management.