A printed circuit board (PCB) is a flat board made of insulating material that connects electronic components using conductive pathways. These pathways are typically made of copper and are etched onto the surface of the board. PCBs are essential in most electronic devices, providing a stable platform for components like resistors, capacitors, and integrated circuits to work together. PCBs come in various types, including single-sided, double-sided, and multi-layer boards, depending on the complexity of the circuit. They are used in a wide range of applications, from simple gadgets to complex systems like computers and smartphones, making them a fundamental part of modern electronics.