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ERC-721 meaning crypto glossary article cover

Definition of ERC-721

ERC-721 or Ethereum Request for Comments 721 is a data standard for creating non-fungible tokens (NFTs). That means each token is unique and cannot be divided or directly exchanged for another token.

This token was proposed by William Entriken, Dieter Shirley, Jacob Evans, and Nastassia Sachs in January 2018 to help track and transfer NFTs within smart contracts.

The token standard became very famous because of a blockchain game called โ€˜CryptoKittiesโ€˜ developed by a Canadian studio, Dapper Labs. In this game, you can collect virtual cats and even breed them.

What are ERC-721 tokens?

The ERC-721 is the token standard used for creating NFTs. Itโ€™s unique and has a different value compared to another token from the same smart contract due to its rarity and visuals

The token can be used on platforms like Uniswap, Rarible, and AtomicMarket, etc. which offer lottery, access keys, tickets, collectible items, and numbered seats for concerts and sports matches. Its uniqueness paves the way for many amazing use cases and possibilities.

There are some other famous tokens like ERC-20 and ERC-1155 but they are different from ERC-721. Hereโ€™s how:

  • ERC-20 vs ERC-721 ๐Ÿ‘‰๐Ÿผ theyโ€™re the total opposite of each other. ERC-20 is used to create similar tokens while ERC-721 is used to create entirely different tokens.
  • ERC-1155 vs ERC-721 ๐Ÿ‘‰๐Ÿผ the former token i.e. ERC-1155 is very versatile as it enables the efficient transfer of fungible and NFTs in a single transaction. ERC-721 token standard, however, works for NFTs only.

NFTs have 50 different use cases that seem to be lumped into one. I think we expect the majority of the [crypto] projects to make use of NFTs.

Raj Gokal, the co-founder of Solana on theย  ERC-721โ€™s NFT concepts

Token functions

The ERC-721 token has several functions that enable it to be owned, traded, and managed. These functions are able to:

  • Return the number of NFTs in the ownerโ€™s account
  • Return the owner of the NFT specified by token ID
  • Approve another address to transfer the given token ID
  • Get the approved address for a token ID
  • Set or unset the approval of a given operator
  • Tell whether a given owner approves an operator
  • Transfer the ownership of a given token ID to another address
  • Safely transfer the ownership of a given token ID to another address

Use cases of ERC-721

Following are the use cases:

Digital art: It can be used as digital art and allow artists and illustrators to add value to the work and sell it forward. OpenSea is one such website that supports selling and buying NFTs as digital art, including ERC-721.

GameFi: GameFi is a burgeoning market in the crypto world today. ERC-721 tokens can very well be used as in-game assets for people to collect. 

An example of this would be Axie Infinity which uses these tokens for its creatures and other in-game characters. In fact, Axies – the game characters – themselves are tokens that are primarily ERC-721.

Tickets: ERC-721 tokens can also be used as a substitute for event tickets which would eventually make the courses all the more interesting. Rarible is another marketplace that supports various types of NFTs, including ERC-721 tokens for digital art, GameFi, and tickets.

Other uses include real estate providing a way for creators to sell their work as a one-of-a-kind item, digital passports, etc.

In conclusion, there is no doubt that the ERC-721 token has created waves in the blockchain space and people love its NFT use case. The token standard has also helped catapult the NFT market to billions of dollars in worth.