Neutrino, once speculated to be massless, has entered into the spotlight by revealing itself of several very interesting properties (through our experiments of course). First of all, neutrinos are no longer massless, tiny though they are, likely in the sub-eV region. Secondly, the three neutrinos associated with the respective lepton are found to have the ability to transform into one another, extending our understanding of the standard model. (In fact, it is through their ability to transform that we are able to speculate upon their masses).
However, our understanding of their properties are still limited, there exist many possibilities as to their roles in the shaping of the universe we have today. The Dayabay Reactor Neutrino Experiment seeks to advance our knowledge about the neutrinos.