Crypto glossary
Transaction hash (TXID)
A transaction hash, or TXID, is the unique identifier of a blockchain transaction, a fixed-length string derived by hashing the transaction's data.
Every transaction on a blockchain gets an identifier produced by running its contents through a hash function. On Bitcoin and Ethereum it is a 64-character hexadecimal string, and Ethereum shows it with a 0x prefix. Change any detail of the transaction and the hash changes completely, so it works as a fingerprint.
The TXID is what users paste into a block explorer to check status, amount, fee and confirmations. Exchanges show it in withdrawal histories, and support teams ask for it when a deposit goes missing. Because transactions are public, sharing a hash with the recipient is a simple way to prove that a payment was sent.
A hash only proves that a transaction exists, not that it is final; until it has enough confirmations it can still be dropped or replaced. It also links to the addresses involved, so publishing one can expose wallet balances and history.
Example
A buyer sends 200 USDC and shares the hash 0x5f2c…e81a with the seller, who opens it in an explorer and sees the transfer confirmed in block 19,000,000.
