We discuss the production of sterile neutrinos in the early universe. While this process is often said to be due to neutrino oscillations, we will argue that many aspects can be better understood by supposing that neutrinos just act like normal particles. We will illustrate this in the production of “reactor-anomaly” neutrinos, Dodelson-Widrow warm neutrinos (arXiv:hep-ph/9303287) and “resonant” warm neutrinos (arXiv:astro-ph/0101524). We will end with a diatribe, proposing that the term “neutrino oscillation” be banned.
(DPhP)