OP\_RETURN

OP\_RETURN is an OPcode whose original behavior was disabled to patch a security vulnerability in Bitcoin’s Script. OP\_RETURN provides a standardized method for embedding arbitrary data in a non-spendable output. It discourages misuse of the blockchain for non-transactional data storage and keeps the UTXO set smaller. The OP\_RETURN transaction data is stored on the Bitcoin blockchain, but the Bitcoin used for this feature cannot be spent again. Thus, most OP\_RETURN outputs will be zero or near-zero amounts. Information stored on the blockchain is censorship-resistant because it is saved on nodes along with the rest of the blockchain data, ensuring it remains accessible as long as the Bitcoin network is active. Importantly, the OP\_RETURN data is excluded from the active memory of a node, so it doesn’t impose as heavy a burden on nodes. The creator of an OP\_RETURN output can choose the amount of Bitcoin to use, which effectively burns that Bitcoin, making it unspendable and removing it from the supply. Read examples of notes that people have left with OP\_RETURN.