Traditionally, cryptocurrencies such as Bitcoin are replaceable. This means that each BTC unit is exactly the same as any other BTC unit and can be exchanged for each other without any additional consideration. Substitutability is one of the fundamental properties of traditional currencies like the US dollar. However, in some use cases, tokens may be non-fungible and most often serve as digital proof of ownership of an underlying asset. For example, NFTs can be used to represent digital art. The once very popular Ethereum-based CryptoKitties game linked tokens to unique images of cartoon cats and allowed users to trade cats by exchanging those tokens.
Another prime example is the tokenization of physical assets, such as stocks or commodities, for use in digital transactions. In this case, the token is a unique asset and cannot be replaced.
Tokens may not interact due to loss of fungibility as a result of less commonly known past activity. For example, if Bitcoins (which are basically replaceable) are being used to pay for illegal goods or to finance illegal activities, once the entire network becomes aware of it, those Bitcoins are unlikely to be accepted on exchanges, resulting in fewer or fewer charges. it won't happen. . and other service providers.