Torque is the twisting force created by an engine rotor. It is the force used to get an engine started while the horsepower enables the engine to sustain power. It measures how much force is being exerted on an object, causing it to rotate.
Horsepower is measured by how quickly the torque is being powered and used.
Torque is normally a factor for manufacturers that build large automobiles capable of hauling extremely heavy loads because a high amount of torque will give the vehicle optimum performance when accelerating and maintaining speed.