A block diagram is a visual representation of a system that uses blocks, lines, and symbols to represent the components of the system and how they interact. It is a useful tool for understanding the structure and behavior of a system, and can be used to analyze and troubleshoot problems. Block
From Wikipedia
A block diagram is a diagram of a system in which the principal parts or functions are represented by blocks connected by lines that show the relationships of the blocks. They are heavily used in engineering in hardware design, electronic design, software design, and process flow diagrams.