A power supply unit (PSU) is a crucial component in computers and electronic devices that converts electrical power from an outlet into usable power for the device. It provides the necessary voltage and current to various components, such as the motherboard, CPU, and graphics card, ensuring they operate efficiently and safely. PSUs come in different wattages and types, including ATX and SFX, to accommodate various system requirements. They often include features like over-voltage protection and cooling fans to maintain optimal performance and prevent overheating. A reliable PSU is essential for the stability and longevity of any electronic system.