Segregated Witness (SegWit)

Overview

Segregated Witness changed Bitcoin‘s transaction and block formats by placing authorization data in a separate witness structure. Legacy nodes can process a compatible view, enabling deployment as a soft fork. Removing witness data from the traditional transaction identifier fixes important forms of third-party transaction malleability. SegWit also measures blocks using weight, discounts witness bytes, and provides versioned witness programs for later script upgrades such as Taproot.

Wallets must generate an appropriate SegWit output type and preserve witness information when signing or broadcasting. SegWit does not eliminate every form of transaction mutation, reduce every transaction’s fee, or make confirmations instantaneous. Benefits depend on the script type, input composition, wallet support, and fee market. For Segregated Witness (SegWit), payment systems should store the exact script or address form and network context used at deposit time. In Segregated Witness (SegWit) implementations, tests should cover mainnet and testnet variants, malformed encodings, unsupported witness versions, and transactions spending or creating the output.

Segregated Witness (SegWit) should be interpreted using the exact network, script or witness version, locking conditions, and encoding rules. In Segregated Witness (SegWit) implementations, similar-looking addresses or script templates can represent different spending requirements and may not be supported by every wallet or service. Validation of Segregated Witness (SegWit) should derive or decode the underlying script rather than relying only on a text prefix. In Segregated Witness (SegWit) implementations, checksum success does not prove spendability, ownership, standard relay policy, or compatibility with the intended asset and network. Wallets supporting Segregated Witness (SegWit) need correct fee estimation, signing data, change handling, and recovery behavior for the relevant output type. In Segregated Witness (SegWit) implementations, watch-only, multisignature, hardware-wallet, and descriptor workflows may require additional metadata beyond the displayed address.