Dark matter - one of the largest space mysteries to date. Don't worry, though; I'm here to give you a thorough overview of what we know - and don't know - including what dark matter is, alternative theories for it, and the various particles that scientists conceive could be composing this mysterious non-baryonic matter. Tune in to get caught up with the rest of us, who are all very, very confused (yet very, very intrigued) about this fantastical concept.