Controllers are used to move objects in SHAPE. The most common use of controllers is to track stage automation.
We have 3 types of controllers, Translate, Rotation and Spline.

Controllers utilise the parenting structure to decide which objects they move. Much like in the real world, we create a track and then place an object on the track. In SHAPE we add a Controller and then child an object to it.

Splines are a special case as we need to child the spline, and the object we wish to move.