Switching power supplies are now very cheap, but this wasn't always the case. The switching power supply gets its name because it switches power on and off thousands of times a second, which turns out to be a very efficient way to do this conversion.
Most consumer electronics, from your cell phone to your television, use a switching power supply to convert AC power from the wall to the low-voltage DC used by electronic circuits. Many electronic components work together to provide smooth power to your laptop.
