A Function Block Diagram (FBD) is a graphical representation used in automation and control systems to illustrate the functions and operations of a system. It consists of blocks that represent different functions, such as logic operations or mathematical calculations, connected by lines that indicate the flow of data or signals. FBDs are commonly used in programming languages like IEC 61131-3 for programmable logic controllers (PLCs). FBDs help engineers and technicians visualize complex processes, making it easier to design, troubleshoot, and optimize control systems. Each block can have inputs and outputs, allowing for modular design and reusability. This approach simplifies the understanding of system behavior and enhances communication among team members involved in automation projects.