What are point on curve deformers?
 
 
 

You can constrain points on a NURBS curve (curve points) to locators. This is useful for deforming individual curves at specific points along the curves. By moving (translating) the locators you can change the shape of the curve without being limited to being able to move only the curve’s CVs. Also, when modeling, you can use point on curve locator constraints to connect two or more curves together so that they intersect. See Set point on curve deformers and Create Deformers > Point On Curve.