What cannot be undone

ethereum.org says a transaction cannot be reversed, and that a wallet cannot easily be recovered.

The keys page, from NIST IR 8202, says that if a key is stolen the thief can sign as the owner, and a transfer they make generally cannot be undone. When the news says crypto was stolen, NIST notes it almost always means the keys were found and used, not that the chain itself was broken.

ethereum.org says a wallet often gives a seed phrase, that the phrase should be written down, and that it should not be stored on a computer. It says the phrase is the only way to recover the wallet. It says there is no customer support in crypto.

The glossary, from NIST, says whoever holds the private key controls what it holds. The seed phrase is what ethereum.org calls the way back to the wallet. This page does not say the phrase and the key are the same string.

On an ERC-20 token, approve names a spender and an amount. The spender may then withdraw up to that amount, more than once. Calling approve again replaces the amount. allowance reads what is left. ethereum.org's token page, last updated 9 Jul 2026, lists those functions.

ethereum.org's guide to revoking access, last updated 6 Jun 2026, says a platform may ask for permission to spend an unlimited number of tokens. Once that permission stands, the spender can move those tokens even after other funds have been taken off the platform. The guide says there is then no recovery. Disconnecting the wallet does not remove the permission. The guide says a permission has no end date.

ethereum.org says the steps it describes are to keep away from untested new projects, to approve only what is needed, and to revoke the access. Revoking is itself a transaction, and it pays a fee. This site does not connect a wallet.