Block Diagram Software, View Examples and Templates Block diagram, as the high-level type of flowchart, is an useful tool in both designing new processes and improving existing processes. Block diagram is extra useful to model the system graphically and show the relationships in the process. It presents a quick overview of major process steps and key process participants, as well as the relationships and interfaces. Block Diagram - Learn about Block Diagrams, See Examples Block Diagram What is a Block Diagram? A block diagram is a specialized, high-level flowchart used in engineering. It is used to design new systems or to describe and improve existing ones. Its structure provides a high-level overview of major system components, key process participants, and important working relationships.