Transaction ID (TXID)
blockchain · technical
A transaction's unique identifier, usually derived by hashing its serialized contents according to the chain's rules.
- Also known as
- Tx Hash, Transaction Hash
A TXID is the identifier wallets and block explorers use to look up a transaction. On Bitcoin-style chains it is commonly the double SHA-256 hash of the serialized transaction without witness data.
TXIDs are useful references, but they are not settlement guarantees. Before confirmation, transactions may be dropped, conflicted, or replaced depending on network policy, and historical malleability issues could change IDs.
Related terms
Transaction
→A serialized state transition that a blockchain can validate, relay, and include in a block.
blockchain · technical
SHA-256
→A 256-bit cryptographic hash function used for transaction IDs, Merkle trees, and proof of work.
hashing · btc · bch
Block Explorer
→An indexed interface for looking up blocks, transactions, scripts or addresses, and other chain data.
tools · fundamentals