Here you can see a exposition model of a Stepper Motor by the German factory Berger Lahr wich is now a Brand of the French Schneider Electric group. This Model was made in the lat 70 early 80s to demonstrate how a step motor work. This model here has a permanent motor as Rotor and starter made out of 4 coils but only two phases. If the state of one phase changes the motor moves a step. This motor here is runned by 12V DC. It has on the PCB an Ozilator to make the motor running. Over various controls you can change the step in 90 or 40° steps left and right turn and also the turning frequency.
In an industrial application they are used with H bridges with an Input Voltage from 24-48V in most cases but there are also models for 12V or 5V Battery supply