The 1N4004 is a general-purpose rectifier diode designed for power rectification, reverse polarity protection, and DC circuit applications. It supports a maximum repetitive reverse voltage of 400V and a forward current of up to 1A, making it suitable for low- to medium-power electronic designs. The axial lead package allows easy through-hole mounting on PCBs and breadboards. Commonly used in power supplies, voltage converters, battery protection circuits, and embedded electronics projects.