Fundamentally there are two types of voltage regulators: linear and switching. The names come from how they operate and how they achieve voltage regulation. Linear regulators tend to be a little cheaper to implement, but they aren’t as efficient as their more complex switching variants.
There are also some “cheap and dirty” methods that some designs use. Below is a brief description and example of each.
Digital ICs like microcontrollers, memory, and shift registers need a stable voltage source to make sure they work as expected. Most circuits are designed with a voltage regulator to accomplish this stability. In theory voltage regulators will vary their output to stay at a set voltage, regardless of how much current the load is drawing. As a load draws a little bit more current, the supply voltage will begin to sag. Conversely when the load is reduced the voltage may rise a little bit. Regulators work to eliminate, well minimize, this change.
Full Tutorial: Voltage Regulator Basics
