A confirmation happens when a transaction is included in a block. One confirmation means the transaction is in one block. Two confirmations means another block has been added on top of it. Each additional block makes reversal harder. Bitcoin exchanges typically wait for six confirmations before crediting a deposit, which takes about an hour. Other networks move faster. Solana confirmations arrive in seconds. The number that matters depends on the value at stake. A coffee purchase needs one confirmation. A six-figure transfer deserves more.

Unconfirmed transactions sit in the mempool, a waiting area. Miners pick transactions from the mempool based on fees. Pay a higher fee and your transaction moves faster. Pay too little and it can sit for hours or get dropped. You can check the status in a block explorer. If it shows pending, it has not been confirmed. If it shows a block number, it is in. More blocks on top means more security. There is no undo button for a confirmed transaction.

Confirmation benchmarks

• Bitcoin — 6 confirmations, roughly 60 minutes
• Ethereum — 12 to 64 confirmations depending on finality rules
• Solana — 1 to 2 seconds for practical finality
• Exchanges — often require their own confirmation thresholds

Waiting is annoying. Waiting is also how you avoid accepting a payment that gets reversed by a chain reorganization.