light particles existing with hadros including electrons, neutrinos and photons
'Light' particles that do not interact via the strong nuclear force. They come in six types (flavours): the electron and its heavier charged cousins, the muon and tau, together with their three neutrinos.
Leptons is the collective term used to describe those fermions which do not experience the strong nuclear force. They are all subject to the weak interactions and those with electric charges experience electromagnetic forces.