Reinforcement
A consequence that follows a behaviour and increases the future frequency of that behaviour.
Reinforcement drives behaviour change. A consequence acts as a reinforcer only if it actually increases the future frequency of the behaviour it follows. It involves adding something preferred (positive reinforcement) or removing something aversive (negative reinforcement).
Reinforcement is defined entirely by its effect on behaviour, not by what you think a learner should want. If you give a student a sticker for completing work and their work completion does not increase, the sticker is not a reinforcer.