To manufacture an electronic product, we usually start by designing a circuit schematic. On the schematic, various specific symbols represent different electronic components, and they are connected by wires. An electronics engineer can clearly see the circuit's working principle and the function of each part through these symbols and connections. If the circuit design is correct, you only need to prepare the necessary electronic components and connect them with wires to make it work. Early electronic products were mostly like this; if you still have a vacuum tube radio from the 1960s or 70s, you can see those messy components and crisscrossing wires.