Given that the only difference between a stationary point and a critical point are that critical points include points whose derivative does not exist and the endpoints of the region and that critical points are more general than stationary points, I suggest that (stationary-point) be renamed to (critical-points). The term "critical point" is also more common than "stationary point," so people asking questions involving critical points are more likely to tag their question correctly. I also suggest making (stationary-point), (stationary-points), and (critical-point) synonyms to (critical-points).
I also think optimization should be kept separate from this tag, as I feel as if (critical-points) should be more for people having trouble finding critical points and the theoretical aspects of critical points without considering optimization.
