Abstract
It is common to think that grounding is necessary in the sense that: if P grounds Q, then necessarily: if P, then Q. Though most accept this principle, some give counterexamples to it. Instead of straightforwardly arguing for, or against, necessity, I explain the sense in which grounding is necessary and contingent. I argue that there are two kinds of grounding: what-grounding and why-grounding, where the former kind is necessary while the latter is contingent.