What causes torque steer?

Torque steer is peculiar to front-wheel drive cars reflecting imbalance when power is sent to the front wheels. It causes a shifting sensation, moving the steering wheel to the left or to the right. It isn't a safety issue, rather it is an annoyance, one that automakers are rectifiying by making use of torque vectoring control, what sends braking power to the inner front wheel as needed.