Rotating an object turns it around its transformation point. The transformation point is aligned with the registration point, which defaults to the center of the object, but you can move the point by dragging it.
Dragging with the Free Transform tool
(you
can skew and scale the object in the same operation).
By specifying an angle in the Transform panel (you can scale the object in the same operation).
Rotate and skew objects by draggingDrag a corner handle to rotate the object.
Drag a center handle to skew the object.
Rotate objects by 90°