This document discusses printed circuit board (PCB) design. It begins with an introduction to PCBs, describing how they mechanically support and electrically connect electronic components using conductive tracks on insulating substrates. It then discusses the basic materials that make up PCBs like copper foil and plating. The document outlines the main fabrication steps for PCBs which include setting up, imaging, etching, drilling, masking, and electrical testing. It also describes the characteristics of through-hole and surface mount technology. The etching and assembly processes are explained in more detail. Finally, the document provides an overview of PCB design and routing software like EAGLE and includes an example of a power supply board.