Additional data or information that can be appended to a crypto transaction on a blockchain is referred to as metadata in blockchain transactions.Metadata is data about data. In the context of blockchain transactions, it includes information that is not directly related to the transfer of cryptocurrency but can provide additional functionality to the transaction.Since this metadata is immediately stored on the blockchain, it is part of the transaction data that is stored there.
When it comes to smart contracts, the contract’s code and accompanying data are kept on the blockchain as on-chain metadata. This covers the functions, state variables and related data of the contract. Each block has headers that provide certain metadata that is easily accessible for verification, like block timestamps, block numbers and transaction IDs. Metadata regarding token properties is frequently maintained on the blockchain for tokens like Ethereum’s ERC-721 and ERC-20.
When a user wants to add metadata to a blockchain transaction, they can do so through a smart contract, which is a self-executing contract with predetermined terms encoded into it. In the above example, the smart contract called MyContract has a publicly readable metadata variable and features a function called setMetadata that enables the metadata to be updated.An individual must communicate with the smart contract by sending a transaction to add metadata to a blockchain transaction. This can be done using libraries like web3.js or ethers.js, or via Ethereum wallet applications.