Suppose you have created an object and you want to reposition some of the points
you chose when creating it. You can do that using the
Anchor rehang mode. First, select an object; its “source” points appear as green triangles (anchors, see Anchors and hangers). By clicking any of them and clicking the destination hanger, you reposition the appropriate anchor and modify the object's geometric dependencies accordingly.
When choosing the new position of the anchor, snap works normally and you can use all the snap modes (see What is snap? What is it good for?).