Work links the concepts of energy and torque. Because we'll only deal with one-dimensional rotational situations, any time there is a torque and an angular displacement, work will be done by the torque.

In a rotational situation:

W = ∫ τ dθ

For a constant torque, W = τ Δθ

Work can be positive or negative, positive when the torque is in the same direction as the displacement and negative when these are in opposite directions.