An electrical diagram is a simplified conventional pictorial representation of an electrical circuit. As represented by the image, the electrical diagram shows the components of the course as simplified shapes and how to make the connections between the devices. A pictorial circuit diagram uses simple images of components, while a schematic diagram shows the components of the circuit as simplified standard symbols. The electrical diagram has electronic symbols to represent the functions, such as wires, batteries, resistors, and transistors, in a schematic diagram. National and international standards cover the graphic symbols used in designing the electrical diagram: IEC, IEC 61131-3, JIC, ANSI, IEEE Std. 91/91a, and AS 1102. At the same time, symbol usage is sometimes unique to engineering disciplines.