Do you know what Confirmation / Block Confirmation means?

Confirmation / Block Confirmation

Definition: In the context of blockchains and cryptocurrencies, a confirmation refers to the successful addition of a transaction to a block, and subsequently, the block being added to the blockchain. Each new block added after that reinforces the security and finality of that transaction, with each new block referred to as an additional confirmation.

Key Points:

  • Assurance of Finality: The more confirmations a transaction has, the harder it becomes to reverse it. This reduces the risk of double-spending or other types of transaction fraud.
  • Standard Confirmation Numbers: Different blockchain platforms and use cases may require different numbers of confirmations to consider a transaction “secure”. For instance, on the Bitcoin network, it’s common to wait for six confirmations.
  • Block Time Influence: The time it takes for a transaction to receive confirmations depends on the block time of the specific blockchain. For instance, Bitcoin’s average block time is approximately 10 minutes, while Ethereum’s is roughly 15 seconds.


  • Double-Spending Problem: One of the primary reasons confirmations are essential in blockchain transactions is to prevent double-spending. Once a transaction is confirmed, it becomes computationally difficult to reverse, ensuring the same coins aren’t spent twice.
  • Security vs. Speed Trade-off: While more confirmations provide higher security, waiting for multiple confirmations can result in longer transaction times. Thus, depending on the urgency and the amount involved, users may accept fewer confirmations.
  • Orphaned Blocks: Occasionally, two miners might solve a block nearly simultaneously. If two versions of the next valid block are broadcast, the network may temporarily diverge in a “fork.” Only one of these chains will become the longest and dominant chain, and the blocks in the shorter chain become “orphaned.” Transactions in an orphaned block would need to be reconfirmed in a subsequent block on the dominant chain.


  • Financial Transactions: For large cryptocurrency transfers, waiting for multiple confirmations ensures that the transaction is irreversible, reducing potential risks.
  • Smart Contracts: On platforms like Ethereum, confirmations are crucial for ensuring the finality of smart contract operations.
  • Trading Platforms: Cryptocurrency exchanges often require multiple confirmations before crediting deposited coins to a user’s trading account.

Related Terms:

  • Zero Confirmations: Refers to a transaction that has been broadcast to the network but has not yet been included in any block. Such transactions are still at risk of being double-spent or not confirmed at all.
  • Mempool: The collection of transactions waiting to be confirmed and added to the blockchain. When the transaction volume is high, it can lead to congestion in the mempool, resulting in longer confirmation times or higher fees for faster confirmations.

In summary, confirmations in the blockchain world refer to the number of blocks added after a transaction’s inclusion, signifying its increasing security and irreversibility. This mechanism plays a pivotal role in ensuring trust and preventing fraud within decentralized systems.

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