Everything you need to understand Bitcoin, in plain English, with no hype and no jargon. This is the explanation we wish someone had given each of us at the start.
Bitcoin is money that works over the internet without a company or government running it. There's no Bitcoin headquarters, no CEO, and no customer service line. Instead, thousands of computers around the world all keep an identical copy of the same ledger — a record of who owns what — and they check each other's work constantly. That ledger is called the blockchain.
Because no single party controls the ledger, nobody can freeze your funds, reverse your transactions, or print more Bitcoin to pay for things. The rules are enforced by math and by everyone watching everyone else — not by trust in an institution.
Bitcoin's supply is capped at 21 million coins, and that cap is enforced by every computer in the network. This is the single most important fact about Bitcoin. Dollars can be printed; Bitcoin cannot. If you hold 1 bitcoin, you will always hold at least 1 of the 21 million that will ever exist.
Don't worry about a whole coin being expensive — each bitcoin divides into 100 million units called sats (satoshis). Nobody starts by buying a whole coin. Stacking sats is the normal way in.
When you own bitcoin, what you really own is a secret key — a very large number that lets you spend coins recorded on the ledger. When you send bitcoin, your wallet uses that key to sign a message that says "move this amount to that address." Miners bundle these messages into blocks roughly every ten minutes, and the network verifies every signature. No valid signature, no spend. That's the whole trick.
Mining is a global competition to add the next page to the ledger. Miners burn real electricity solving a puzzle, and the winner earns newly issued bitcoin plus transaction fees. The energy cost is the point: it makes rewriting history absurdly expensive, which is what keeps the ledger honest without a referee.
Nothing here is financial advice — we're a community of learners, not advisors. The best way to get comfortable is to come to a meetup and ask the questions you think are too basic. They aren't.