1. general

OP_RETURN is an opcode in Bitcoin's scripting language that allows a small amount of arbitrary data to be written onto the blockchain. It marks the output as unspendable, effectively making it a mechanism for embedding data into the blockchain without cluttering the UTXO set.


"A simple use of OP_RETURN could be to record a short message or a hash of a document onto the Bitcoin blockchain."

2. usage

OP_RETURN is useful for building on-chain protocols to extend Bitcoin's functionality. It allows developers to create a wide range of applications, from token systems to decentralized social media platforms, by leveraging the immutability of the blockchain.


"The Omni Layer protocol uses OP_RETURN to issue and transfer custom tokens on the Bitcoin blockchain."

3. limitations

While OP_RETURN is a powerful tool, it has limitations. The amount of data that can be included in an OP_RETURN output is currently limited to 80 bytes. This encourages efficient use of blockchain space and helps maintain the scalability of the network.


"If you need to store a large amount of data using OP_RETURN, you would typically store a hash of the data, rather than the data itself, due to the 80-byte limit."

4. controversy

The use of OP_RETURN has been a topic of debate within the Bitcoin community. Some argue that the blockchain should be used solely for financial transactions, while others see value in using it as a decentralized, immutable data store.


"Despite the controversy, the use of OP_RETURN has grown over the years, with many innovative applications being built using this opcode."

* All terms and definitions may update as the Cryptionary improves.