The switching regulator is increasing in popularity because it offers the advantages of higher power conversion efficiency and increased design flexibility (multiple output voltages of different polarities can be generated from a single input voltage). 

The primary advantages of a switching regulator is its high efficiency, smaller size and low heat output.

Switching regulators operate in step up, step down, and inverting modes.

The four most commonly used switching converter types are Buck, Boost, Buck-Boost, and Flyback

Also, there are multiple-transistor converter topologies such as:

Push-Pull:  A two-transistor converter that is especially efficient at low input voltages.