This document discusses different types of engine starters used to start internal combustion engines. It describes impulse starters, inertia starters, electric starters, auxiliary power units, turbo-starters, cartridge turbo-starters, and liquid fuel turbo-starters. The main purpose of starters is to provide the initial torque required to start engines by utilizing mechanisms like springs, flywheels, electric motors or combusting fuels to turn the engine crankshaft.