Transaction
A transaction is a record of coins moving from one address to another, signed with the sender's private key. Once it lands in a block and gathers confirmations it becomes part of the blockchain permanently: it cannot be reversed.
How it works
A wallet assembles the transaction, signs it with the key and broadcasts it. It joins the shared queue of pending transactions, the mempool, and waits for a miner or validator to include it in a block. The higher the offered fee, the sooner that happens.
Once in a block, confirmations start to accumulate: every block added on top makes reversal more expensive. Exchanges typically wait between one and six confirmations depending on the amount and the network.
While a transaction sits in the mempool it can be replaced by resending the same operation with a higher fee. After it enters a block nothing can be changed.
If it gets stuck
- Check the explorerThe transaction hash shows whether it is still in the mempool or already in a block. Do that before writing to support.
- Speed it up with a fee bumpMany wallets can resend the operation with a higher fee, which cancels the earlier version.
- A low fee means a long waitOn a busy network a cheap transaction can wait hours and eventually drop out of the mempool.
- A wrong address cannot be fixedA confirmed transfer is final. The only defence is a small test send to any new address.