A printed circuit board (PCB) is a flat board made of insulating material that supports and connects electronic components. It has conductive pathways, usually made of copper, which allow electricity to flow between different parts of a circuit. PCBs are essential in most electronic devices, from smartphones to computers, as they provide a compact and organized way to connect various components. PCBs can be single-sided, double-sided, or multi-layered, depending on the complexity of the circuit. They are designed using computer-aided design (CAD) software, which helps engineers create precise layouts. The manufacturing process involves etching the copper layers and adding components like resistors and capacitors, ensuring reliable performance in electronic applications.