📡 Sending a Transaction

Something very different happens

Hit "send" on a banking app and a company quietly updates a database.

Hit "send" on Bitcoin, and something very different happens.

Signing

A transaction is a message: "Move this amount from this address to that one."

It's signed with your private key as cryptographic proof that you — and only you — authorised it.

The key itself never leaves your device. Only the signature travels.

Broadcasting

Once signed, the transaction is broadcast to computers (nodes) all over the world.

It isn't sent through one central server that could block it, delay it, or alter it.

You're not asking permission. You're announcing a fact.

Confirmation

Miners bundle pending transactions into blocks.

Once your transaction is included in a block, it has 1 confirmation.

Every block added after that makes it exponentially harder to reverse.

Try it: Transaction flow

Put the five stages in order — each one reveals what really happens.

Hit send on Bitcoin and five things happen in order: your key signs it, it broadcasts to the world, it waits in the mempool, a miner packs it into a block, and it confirms. Put the journey in order and see what each stage really does. Open the Transaction Flow tool →

Quick check: What proves you authorized a transaction?

1. Your digital signature, created with your private key ✓
2. A confirmation email from your wallet provider
3. The miner who includes it in a block

The signature can only be produced by the private key — and anyone can verify it without ever seeing that key.

Quick check: What happens to a transaction's security as more blocks are added after it?

1. Nothing changes after the first confirmation
2. It becomes harder and harder to reverse ✓
3. It slowly expires and must be re-sent

Reversing it would mean redoing the proof-of-work for that block and every block after it. Each new block raises that cost.

Next up

But who actually builds these blocks — and why can't they cheat?