MiniBooNE is a Fermilab neutrino experiment built to test whether puzzling results from the LSND experiment signaled new physics. Using a beam mostly of muon neutrinos and a Cherenkov detector filled with mineral oil and lined with photomultiplier tubes, it searched for excess electron neutrino events that would show neutrinos changing flavor in flight. Earlier work had already established neutrino oscillations and mass, but LSND suggested behavior that did not fit neatly with known parameters. Beginning data collection in 2002, MiniBooNE produced mixed results that kept the issue open and made it a significant step in the search for sterile neutrinos and physics beyond the Standard Model.