Stepper motors are used in many applications in automating manufacturing. This is not an exhaustive presentation but more than enough to get you started with them. Lectures with the same title are different lectures on the same subject.
1 - How does a Stepper Motor work?
2 - How does a Stepper Motor work?
3 - How does a Stepper Motor work?
4 - Identifying the wires on your Stepper Motor.
6 Wires Unipolar / Bipolar Motor
5 Wires Unipolar / Bipolar Motor