If Bitcoin were a large city, about 2,100 square kilometers like Los Angeles or Bangkok, the commonly transacted piece would be like the tip of a ballpoint pen (1 square millimeter). These tiny pieces—often called sats, zaps, or little bits of Bitcoin—are what Bitcoiners zap to each other as tips. For context, a cent is worth about 10 sats, while a dollar is about 1,000 sats.

The "BTC" unit (annoyingly also sometimes called Bitcoin) is 100 million times larger—100 square meters, about the size of a 2-bedroom apartment. And the total area of Bitcoin that will ever exist is 21 million times larger than a BTC and 2,100 trillion times larger than a sat.

But it all adds up to just one Bitcoin. Every sat you zap or BTC trade you make is simply an exchange of different-sized pieces of that one finite #Bitcoin.