We think we have a pretty good handle on what life is, but the reality is that thinks we think of as living are just a subset of possible chemistries and mechanisms by which life could evolve and function. To really understand what it means to be alive and recognize alien existences radically different from everything we think we know means we need to ask ourselves some very weird and complicated questions like what life, and what sort of things could we expect to be the most common lifeforms in the universe.