In this video session, we will be discussing about electronic component called a diode. A diode is a semiconductor component that acts as a one-way switch for the current. A diode is a semiconductor device, which is made by connecting two semiconductor materials. There are many types of diodes like Zener diode, light-emitting diode, and SMD diode, used in electronic development. To become a hardware repairing expert, knowing this component’s features and its testing procedures are very important. In this session we will learn what is a diode, how does it look like, the architecture of diode, Types of a diode, the marking of a diode on PCB and circuit, the work of diode in DC circuits, how to Identify bad diode, and how can we test a diode using a multi-meter.