The price of a bitcoin topped $900 last week, an enormous surge in value that arrived amidst Congressional hearings where top U.S. financial regulators took a surprisingly rosy view of digital currency. Just 10 months ago, a bitcoin sold for a measly $13.

The spike was big news across the globe, from Washington to Tokyo to China, and it left many asking themselves: “What the hell is a bitcoin?” It’s a good question — not only for those with little understanding of the modern financial system and how it intersects with modern technology, but also for those steeped in the new internet-driven economy that has so quickly remade our world over the last 20 years.