When you hear about a switching power supply, you think of a system that uses an inductor and a switch to redistribute energy from the input to the output. But the original switching power supply ...

The common type of power supply used with computers and other electronic equipment. The "switching" comes from switching a transistor on and off to create square waves for input to a transformer.

The first thing I ever built without a kit was a 5 V regulated power supply using ... Well, you buy a switching power supply IC, add an inductor and you are done. Class dismissed.