Another component is the AC adapter. It is the heavy black box usually located around the middle of the AC power cord. Its job is to convert the alternating current from the grid into direct current that is usable by the laptop.
The third component is the surge protection system. It is dispersed throughout the power supply and helps keep the laptop from shorting itself, or sometimes blowing itself up when a very strong current passes through it. The first line of defense is the grounding found on the wall jack. The second is in the AC adapter. The third one is in the power board. All of these work as redundant systems to ensure the laptops safety.
Each component of the power supply has its own purpose. Other parts of the computer, such as the cooling fans, help to enhance their protective and distributive functions."