Why is holding current needed in stepper motors?

Question

In an application where there is no force applied to the torque requirements, why is the holding current required? For instance, in a rack and pinion use, where there is no force on the rack.

Answer 1

To hold the position.  A stepper motor is use to move a certain amount and then hold that position.

Answer 2

if there is no torque applied to the motor, no holding current is required and on stepper motors that incorporate a position encoder (rare - because one advantage of a stepper is that (usually) you don't need a position encoder) little if any holding current is applied unless movement is detected

holding currents are the norm because they cover all applications

Answer 3

The motor would drift if there wasn't a magnetic field holding it in place. There's no mechanical latching or anything.