I don't really understand, I used to think that a cryptocurrency unit was non-fungible ? As I'm a computer scientist many of my friends ask me questions about cryptocurrency and nfts, even though I know nothing about it. Five years ago, I learned the basics so I could answer, and I understood that one specificity of a cryptocurrency was to resolve the double-spending problem.

In that sense, one cryptocurrency unit was fundamentally unique, not duplicable, if you try to use it twice or to copy it, it wouldn't work. I even explained it to some friends with a parallel in art world : if you had one piece of art associated to a block in a blokchain, you couldn't duplicate it, but only trade it with another one, and you would always know that it's specifically this one and not another one.

Now, I hear a lot about the NFTs, especially the ethereum ones, and it seems to me that it describes exactly this situation : a unit that is unique, and specifically identifiable.

The only difference I can think of, is that because of the idea associated with one unit when it's a coin, nobody cares to posses the coin A or the coin B as long as their value is identical (1 ether for example), but if the unit is a piece of art the value is dependent of the sociological and cultural context, so we care to exchange one "bored ape" with another.

Am I wrong ? Is there a technological distinction between cryptocurrency and NFTs ? Or is it a different application of the same technology ?

It seems to me that coins are non-fungible, but we don't care (except for real coin when there is a special limited edition, then a 1$ coin can have a value of more than 1$)

2 Answers 2


I think what you have written is true. But the concept of fungibility has its niches. Bitcoin is fungible, but of course, each coin of bitcoin is different. You can exchange one bitcoin for another without having any change in the value. Bitcoin uses UTXO model. It basically tracks the number of bitcoins a account has based on the input and output of transactions. But still the value and properties of one bitcoin is equal to the another.

However, NFTs are non-fungible for fundamental difference that each token has its own value and properties. Like BORED APE with token id 1 vs BORED APE with token id 1000. They can't be exchanged. Though they belong to same technology, same blockchain, they have different properties. So, they are not exchangeable nor fungible.


I think to answer to this question there needs to be more context to address the terms fungible and non-fungible.

The openzeppelin docs are a great resource for these concepts.

Tokens in general https://docs.openzeppelin.com/contracts/3.x/tokens#different-kinds-of-tokens

ERC20 Tokens (fungible) https://docs.openzeppelin.com/contracts/3.x/erc20

ERC721 Tokens (NonFungible) Used for NFTs https://docs.openzeppelin.com/contracts/3.x/erc721

The ERC721 EIP https://eips.ethereum.org/EIPS/eip-721#abstract

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