Nereid said, "'hot dark matter' ('dark matter' which is, or was, moving at relativistic speeds; neutrinos are an example)"

I was under the impression that neutrinos have mass, is that correct? (and do we know how much mass? As much as an electron? Less?) Assuming that they do have mass, I must infer that by "relativistic speeds" you mean speeds approaching, but not reaching, c. Is that correct? I just want to make sure I`m clear on this...