A circuit diagram is a visual representation of an electrical circuit. It uses symbols to depict various components like resistors, capacitors, and batteries, showing how they are connected. This diagram helps engineers and technicians understand the layout and function of the circuit, making it easier to design, troubleshoot, and repair electrical systems. In a circuit diagram, lines represent wires that connect the components, while standardized symbols indicate the type of each component. By following the diagram, one can trace the flow of electricity and identify potential issues, ensuring the circuit operates as intended.