You've heard the word "blockchain" many times now, but probably not quite as many as you've heard the word "bitcoin." Yet you surely have a sense that the referents of those two words have a connection, and even if you haven't yet been interested in either, you may well know that blockchain, a technology, makes Bitcoin, a currency, possible in the first place. Their sheer novelty has already given rise to a mini-industry of explainer videos, more of them dealing directly with bitcoin than blockchain, but in time the latter could potentially overtake the former in importance, to the degree that it becomes as vital to society as the protocols that undergird the internet itself.