==== EIP 721: ERC-721 Non-Fungible Token Standard  ====
[[dido:public:ra:xapend:xapend.b_stds:defact:ethereum:eip| Return to Ethereum ERCs ]]

  : **Note**: The following is an excerpt from the official Ethereum site. It is provided here as a convenience and is not authoritative. Refer to the original document as the authoritative reference.

<table>
<caption>Data sheet for Non-Fungible Token Standard</caption>
| Title                      | Non-Fungible Token Standard |
| Author                     | William Entriken, Dieter Shirley, Jacob Evans, Nastassia Sachs |
| Status                     | Final |
| Created                    | 2018-01-24  |
| Description                | [[http://eips.ethereum.org/EIPS/eip-721]] |
| Specification              | [[http://eips.ethereum.org/EIPS/eip-721#Specification]] |
| Category                   | ERC |
| Requires                   | [[dido:public:ra:xapend:xapend.b_stds:defact:ethereum:eip:erc_0165|ERC-165]] |
</table>

=== Abstract === 
//The following standard allows for the implementation of a standard [[dido:public:ra:xapend:xapend.a_glossary:a:api|API]] for [[dido:public:ra:xapend:xapend.a_glossary:n:nft]] within smart contracts. This standard provides basic functionality to track and transfer NFTs.//

//We considered use cases of NFTs being owned and transacted by individuals as well as consignment to third party brokers/[[dido:public:ra:xapend:xapend.a_glossary:w:wallet|wallets]]/auctioneers (“operators”). NFTs can represent ownership over digital or physical assets. We considered a diverse universe of assets, and we know you will dream up many more://

    * //Physical property — houses, unique artwork//
    * //Virtual collectables — unique pictures of kittens, collectable cards//
    * //“Negative value” assets — loans, burdens and other responsibilities//

//In general, all houses are distinct and no two kittens are alike. NFTs are distinguishable and you must track the ownership of each one separately.//

=== Motivation === 
//A standard [[dido:public:ra:xapend:xapend.a_glossary:i:interface|interface]] allows wallet/broker/auction applications to work with any NFT on Ethereum. We provide for simple ERC-721 smart contracts as well as contracts that track an arbitrarily large number of NFTs. Additional applications are discussed below.//

//This standard is inspired by the [[dido:public:ra:xapend:xapend.b_stds:defact:ethereum:eip:erc_0020|ERC-20]] token standard and builds on two years of experience since EIP-20 was created. EIP-20 is insufficient for tracking NFTs because each asset is distinct (non-fungible) whereas each of a quantity of [[dido:public:ra:xapend:xapend.a_glossary:t:tokens|tokens]] is identical ([[dido:public:ra:xapend:xapend.a_glossary:f:fungible|fungible]]).//

//Differences between this standard and EIP-20 are examined below.//