What is a PSBT (partially signed Bitcoin transaction)?
A standard format for passing an unsigned or partly signed payment between wallets and signers, until it is fully signed and broadcast.
Not to be confused with: a broadcast transaction — it cannot confirmTransactionA signed instruction that moves bitcoin: it spends some earlier outputs and creates new ones, each with an amount and an owner..
Defined in BIP-174, a PSBT bundles a payment with the information each signer needs, such as which inputs belong to which keys. A coordinator can build it on one machine, signers sign on others, and nobody has to share keys.
Hardware walletsHardware walletA small device that holds your private keys and signs payments inside itself, so the keys never touch your internet-connected computer or phone. and multisigMultisig (multi-signature)A wallet whose coins need signatures from several keys, such as 2 of 3, so no single key can spend alone. setups rely on it: the unsigned payment travels to the offline device, comes back signed, and only then is broadcast. A PSBT is not a payment yet — it has no transaction ID and cannot confirm.
References
- Bitcoin Improvement Proposals, “BIP-174: Partially Signed Bitcoin Transaction Format”.