# ERC-7231
Bluwhale ID - ERC 7231
[ERC-7231](https://eips.ethereum.org/EIPS/eip-7231) extends[ ERC-721](https://eips.ethereum.org/EIPS/eip-721) by binding individuals’ Web2 and Web3 identities to non-fungible tokens (NFTs) and Soulbound tokens (SBTs). By binding multiple identities, aggregated and compossible identity information can be verified, resulting in more beneficial on-chain scenarios for individuals, such as self-authentication, social overlapping, commercial value generation from user targeting, etc. By adding a custom schema in the metadata, and updating and verifying the schema hash in the contract, the binding of NFT and identity information is completed. For details, visit:[ EIP-7231](https://eips.ethereum.org/EIPS/eip-7231).
In an enhanced version, identities are structured within a Merkle tree, where each leaf represents a distinct ID. This configuration allows users to disclose specific IDs as needed, concealing their full identity spectrum from the computation layer. This approach minimizes the risk of data leakage and enhances the efficiency of data transfer.
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