A future version of this page will describe what Kepler is and why Sputnik uses it. For now, however, this site assumes that you are a Kepler user, since Sputnik uses a version of Kepler that has not been fully documented. If you've never heard of Kepler, please come back in a few weeks and we'll be able to point you too Kepler's documentation (or package Kepler together with Sputnik).