A neutrino (predicted by Wolfgang Pauli in 1932 and roughly meaning "little neutral" one in Italian) is a
very small particle. It was not discovered until over twenty years later in an experiment in
It is thought to have almost no or indeed no mass.
It has no charge
It can pass though large distances of matter with virtually no loss of energy
It moves close to the speed of light
It causes little or no ionisation in its path
It is produced as a result of the decay of a neutron into a proton and an electron (actually this process produces an antineutrino but that makes the explanation even more complex)
It is really produced in the production of a neutron and a positron from the addition of energy to a proton
Neutrinos are detected in huge tanks thousands of metres below ground level. The vast amount of earth and rock above the tanks filters out all but the highly penetrating neutrinos.