A neutrino (/nuːˈtriːnoʊ/ or /njuːˈtriːnoʊ/) (denoted by the Greek letter ν) is a lepton, an elementary particle with half-integer spin, that interacts only via the weak subatomic force and gravity. The mass of the neutrino is tiny compared to other subatomic particles. They are the only identified candidate for dark matter, specifically hot dark matter. Neutrinos come in three flavors: electron neutrinos (ν e), muon neutrinos (ν μ), and tau neutrinos (ν τ). Each flavor is also associated with an antiparticle, called an "antineutrino", which also has no electric charge and half-integer spi...