This is a very good explanation actually. > Pro tip: If an article includes a diagram with a triangle, stop reading Exactly. I've seen many explanations that

This is a very good explanation actually. > Pro tip: If an article includes a diagram with a triangle, stop reading Exactly. I've seen many explanations that try to turn it into a trade-off between three things analogous to the maxim "resources, features, schedule: fix any two and the third must change".