Ray NP starts at point N as the fixed endpoint and goes off forever in the direction of point P.
The opposite would be to turn 180 degrees and go the other way. So we start at N and instead go off forever toward point M. In either case, the starting point is still the same (point N).
When naming rays, the order is important. Ray NM is different from ray MN. This is because the first letter is the fixed end point (that doesn't go off forever in one direction).
