Transactions · 25 / 86 · 2 min
Transactions and finality
A transaction is a signed request to change the record. It is final when rewriting it would cost more than anyone will pay. Pending is not final.
More confirmations mean a rewrite costs more. An exchange may wait longer than the chain.
A worked case
Someone ships goods because a wallet shows pending. The transaction is replaced with a higher fee by the sender. The goods are gone. The payment is not.
What was sent
Look at the asset, the amount, and the destination before you sign. After it is in a block and buried under more blocks, the chain will not undo it for you.
Paid twice
You may pay a network fee even if the contract rejects the action. You may also pay the project's own fee inside the same click.
An exchange calling something complete means their database updated. Check the chain if the destination was supposed to be yours.
Pending is a suggestion
A transaction is final when rewriting it would cost more than anyone will pay. Before that it is a message on the network. Bitcoin lets the sender replace a transaction with a higher fee, which is how a stuck payment gets unstuck, and also how a payment you already trusted can be swapped. Ethereum's mempool is a public waiting room. Seeing a hash is not seeing a block.
Exchanges learned this the expensive way and then made you wait. A deposit may need several confirmations before they credit it, because a payment with one confirmation has been rewritten in the past when the incentive was large enough. The 2010 value overflow was a bug, not a double spend, but it is the historical reminder that the living network has abandoned a chain when it had to. Ordinary life is quieter: people ship goods against a pending screen, and the sender walks.
Wait until it is buried before you treat it as done. Ask the exchange how many confirmations it wants, and do not promise the goods on a smaller number because you are in a hurry.
Read it yourself
These links are the record. They are not a recommendation, and they are not instructions. A news story or a court paper can still be wrong about a detail. The check does not change because a famous name is in the story.
Apply the check
Open a question. The line is about this topic. It is not a verdict that anything is safe.
Miners or validators who include the transaction.
The sender, until it is buried. The chain's rule after that.
A rewrite, while it is shallow. Not a support desk, once it is deep.
Check yourself
Can you call support to reverse a confirmed personal transfer?
No. The chain will not undo it because you changed your mind.
After this you can read the destination before you sign, and treat pending as unfinished.