How does Bitcoin actually work?

Here’s the puzzle Bitcoin had to solve: if there’s no bank keeping score, what stops someone from spending money they don’t have, or just rewriting the record in their favor? The answer is surprisingly elegant, and you don’t need any math to get it.

It all runs on a shared ledger

Picture a giant public notebook that lists every Bitcoin transaction ever made. That notebook is the blockchain: “block” because entries are bundled into pages called blocks, “chain” because each new page is locked onto the one before it. To know your balance, you just add up what the ledger says is yours.

Thousands of copies, no head office

The trick is that this notebook isn’t kept in one place. Tens of thousands of computers, called nodes, each keep their own full copy and check every new entry against the rules. Try to sneak in a fake transaction and the rest of the network simply rejects it. There’s no single copy to hack and no central referee to bribe.

No one trusts anyone. Everyone trusts the rules, and checks them.

Who writes the next page?

Roughly every ten minutes, a new page of transactions gets added. The right to write it is earned by miners: computers that race to solve a hard puzzle that’s expensive to crack but instant to verify. The winner adds the next block and earns some new Bitcoin for the effort. That cost is what makes rewriting history wildly impractical: you’d have to out-spend the entire honest network.

Why you can trust it without trusting anyone

Banks ask you to trust them. Bitcoin replaces that trust with something you can verify: open rules, a public ledger, and thousands of independent computers all enforcing the same thing. No good faith required. Just math and a lot of witnesses.