Boost converter
also known as: Step-up converter
A switching regulator that steps voltage UP: the inductor is charged from the input, then its stored energy is released on top of the input voltage into the output. A single battery cell becomes a 5 V rail this way.
In practice
Boost converters can't current-limit through the inductor-diode path at startup, and the output can never go below Vin minus a diode drop — two surprises worth knowing before the bench finds them for you. Input current exceeds output current; size the source accordingly.