What is "quantum supremacy" and is it a big deal?

Quantum supremacy is the idea that a quantum computer, a computer using the principles of quantum mechanics, can solve a problem that a classical computer cannot solve. The reason we're talking about it this week is that Google says, after billions of dollars in investment and years of work, that they actually have built such a quantum computer and it has in fact, solved a problem in 200 seconds, that it would take ten thousand years for regular computers to solve. IBM fought back and said that's not true. But is quantum supremacy a big deal? Absolutely. Is what we saw this week quantum supremacy? That's a harder question.