ERC721 Definition: Understanding the Standard for Unique Non-Fungible Tokens (NFTs)

  • 👤 Matthieu Lamarque -
  • 📅 April 27, 2023 14:51 -
  • Categorie: tech
ERC721 Definition: Understanding the Standard for Unique Non-Fungible Tokens (NFTs)

ERC721: a standard

ERC721 is a smart contract standard based on the Ethereum blockchain that is used to create unique and non-fungible assets, also known as NFTs, on the Ethereum blockchain.

NFTs created with the ERC721 standard are unique, meaning each NFT has its unique identifier. This allows NFT owners to prove the authenticity and ownership of their NFTs.

The ERC721 standard also enables the secure and transparent transfer of ownership of these NFTs between different users without the need for an intermediary.

The ERC721 standard has opened the door to many applications in areas such as video games, digital art, collectible tokens, event tickets, virtual properties, and more.



Understanding the Main Functions of ERC721

The ERC721 standard defines several functions that developers can implement in their smart contracts to create NFTs that conform to this standard. Here are the main functions of the ERC721 standard:


  1. balanceOf(address owner): This function retrieves the number of NFTs owned by a specific owner.
  2. ownerOf(uint256 tokenId): This function retrieves the address of the owner of a specific NFT identified by its unique ID.
  3. safeTransferFrom(address from, address to, uint256 tokenId, bytes data): This function transfers the ownership of an NFT from the from address to the to address. The function can also include additional data in the form of bytes.
  4. safeTransferFrom(address from, address to, uint256 tokenId): This function is similar to the previous function but does not take any additional data.
  5. transferFrom(address from, address to, uint256 tokenId): This function transfers the ownership of an NFT from the from address to the to address. This function is less secure than the two safeTransferFrom functions because it does not verify if the recipient is a contract that can receive the NFT.
  6. approve(address to, uint256 tokenId): This function allows an NFT owner to give permission to a specific address (to) to transfer the NFT.
  7. setApprovalForAll(address operator, bool approved): This function allows an NFT owner to give permission to an address (operator) to transfer all of their NFTs.
  8. getApproved(uint256 tokenId): This function retrieves the address to which an NFT owner has authorized the transfer of a specific NFT (tokenId).
  9. isApprovedForAll(address owner, address operator): This function checks if an address (operator) is authorized to transfer all of the NFTs of a specific owner (owner).

By using these functions and customizing them according to their needs, developers can create ERC721-compliant smart contracts to create unique and non-fungible NFTs.

The ERC721 standard was originally created for the Ethereum blockchain, but it is not limited to Ethereum. The ERC721 standard is a type of smart contract that can be implemented on any blockchain that supports smart contracts. In fact, there are now several blockchain platforms that have implemented their own version of the ERC721 standard, including Binance Smart Chain, Flow, and others.

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