What is a Confirmation?
The process by which a Bitcoin transaction is verified and added to the blockchain. Each new block that's added after your transaction counts as an additional confirmation. Most exchanges and services consider a transaction secure after 6 confirmations (about 60 minutes).
Why It Matters
Confirmations measure the security of a Bitcoin transaction. When you first send bitcoin, the transaction enters the mempool as unconfirmed. Until it's included in a block, it's not yet final—technically, a powerful attacker could still double-spend the same coins (though it's unlikely). Each new block that comes after your transaction is one more confirmation, representing additional computational work an attacker would need to redo to reverse your transaction. After six confirmations, the work required to reverse your transaction exceeds reasonable attack costs. Understanding confirmations helps you know when you can trust a payment has completed. For small amounts or trusted parties, one or two confirmations might be enough. For significant transactions, six or more is standard.
How It Works
Your transaction gets one confirmation when miners include it in a block. When the next block is mined, that's two confirmations. This continues for each new block. The longer the chain that follows your transaction, the more computationally expensive it becomes to rewrite that history. To reverse a six-confirmation transaction, an attacker would need to redo the mining work for all six blocks plus extend their chain further—an enormous undertaking. This is why waiting for more confirmations increases security. The six-confirmation standard arose because it typically represents about 60 minutes of mining time, a threshold that balances practical finality with accessibility.