Torque, moment, or moment of force is rotational force. Just as a linear force is a push or a pull, a torque can be thought of as a twist to an object.
Torque is a measure of how much a force acting on an object causes that object to rotate. The object rotates about an axis, which we will mark as point 'O', called pivot.
Torque is rotational equivalent of force. It is product of force and the distance from which it is applied from the pivot(O)
Torque= force × displacement.
Now, generally speaking, force is measure of how much work you need to do to move a body linearly(in straight line). But it is completely different in rotational motion. If you push a door from a point far away from its hinge, you can easily open or close it. But, if you push same door close to its hinge, it will be very much difficult. To measure this effect of force, in rotational motion, we use term torque.