# What is a confirmation?

A transaction gets one confirmation when a block includes it, and each later block adds one more. THORChain waits for more confirmations on larger transfers, up to a maximum set for each chain.

Also called confirmations or block confirmations.

## How confirmations add up

Once a block includes a transaction, the transaction sits at depth one, which is its first confirmation. Every block added after that counts as one more, so if the next block arrives, the transaction has two confirmations.

Six confirmations is a long-standing convention for Bitcoin.

## Why more confirmations are safer

- Every extra block makes it harder to reverse the transaction, because an attacker would have to rebuild every block from the transaction onward.
- An attacker's chances also depend on how much of the mining power they control.
- A transaction with no confirmations is relatively cheap to reverse.

## How THORChain uses confirmations

THORChain counts confirmations on chains such as Bitcoin and Ethereum, and it holds a transfer until the count is reached. It starts counting at the block in which its nodes first see the transfer. Cosmos-style chains, which finalize blocks instantly, skip the count.

The number is set by a formula. The value of the transfer is divided by the block reward of that chain, which is the new coin a miner earns for each block. The result is multiplied by a factor set for each chain, and it is capped at a maximum set for each chain.

So a larger transfer waits for more blocks, until the cap is reached.

## Related terms

- [Mempool](https://redacted.gg/glossary/mempool.md): The mempool is the waiting area for valid transactions that no block has included. Each node keeps its own copy, so anyone running a node can see the transactions in it before they are confirmed.
- [UTXO](https://redacted.gg/glossary/utxo.md): Bitcoin keeps no account balances. It keeps unspent transaction outputs, or UTXOs, which are the coins a wallet can spend, and each payment spends whole UTXOs and creates new ones.
- [THORChain](https://redacted.gg/glossary/thorchain.md): THORChain is a network that swaps native coins across chains, such as Bitcoin for Ether, with no bridges and no wrapped tokens. The coins sit in vaults on their home chains, secured by about 100 independent node operators.
- [The wait](https://redacted.gg/glossary/deposit-wait.md): In Redacted, new money waits about two hours before it can be used privately. That gap keeps a deposit from being matched to what you do with it minutes later, so your crowd stays at its full size.
- [Native cross-chain swap](https://redacted.gg/glossary/cross-chain-swap.md): A native cross-chain swap trades a coin on one chain for a coin on another, for example Bitcoin for Ether, by moving the real coins between vaults instead of minting wrapped copies on a bridge.

Sources: [Confirmation, Bitcoin Wiki](https://en.bitcoin.it/wiki/Confirmation), [Transaction delays, THORChain developer docs](https://dev.thorchain.org/concepts/delays.html)
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Page: https://redacted.gg/glossary/confirmation/