Neutrinos
The neutrino is an extremely small particle, just slightly bigger than the well known electron. The neutrinos get their name because they have zero electric charge, meaning that they are perfectly neutral. Because of this, they are snuffled out by their non neutral counterpart, so other methods of detecting them have to be taken.
The Identity Crisis
Neutrinos are very unpredictable, and come in three flavours, but they are the only particles able to have an identity crisis, they can change their oscillation speed and appear to be a different flavour than what they actually are.
The identity crisis is caused by something called neutrino oscillation. Because they oscillate at certain speeds, being the way they are detected, and if you are not careful, these particles will flip their oscillation speed and frequency, therefore seeming like a completely different particle.
Neutrino Facts
A neutrino is much like all the other leptons, being the group that does not participate in strong nuclear reactions, but plays an important role in weak nuclear reactions.
The neutrino is the most abundant particle in the universe, and interacts with barely anything due to its near zero mass and its completely zero electric charge.
An electronvolt is a unit of measurement defined by the amount of kinetic energy a single electron gains from accelerating from rest by a electric potential difference of one volt in a vacuum. A neutrino has 0.120 electron volts of mass, and has an electric charge of 0.
Links
Wikipedia: Neutrino Oscillation, Neutrino, Leptons.