Non-fungible tokens (NFTs) are assets that have been tokenized via a blockchain. They are assigned unique identification codes and metadata that distinguish them from other tokens.
NFTs can be traded and exchanged for money, cryptocurrencies, or other NFTs—it all depends on the value the market and owners have placed on them. For instance, you could use an exchange to create a token for an image of a banana. Some people might pay millions for the NFT, while others might think it worthless.
Cryptocurrencies are tokens as well; however, the key difference is that two cryptocurrencies from the same blockchain are interchangeable—they are fungible. Two NFTs from the same blockchain can look identical, but they are not interchangeable.
NFTs were created long before they became popular in the mainstream. Reportedly, the first NFT sold was "Quantum," designed and tokenized by Kevin McKoy in 2014 on one blockchain (Namecoin), then minted and sold in 2021 on Ethereum.
NFTs are built following the ERC-721 (Ethereum Request for Comment #721) standard, which dictates how ownership is transferred, methods for confirming transactions, and how applications handle safe transfers (among other requirements). The ERC-1155 standard, approved six months after ERC-721, improves upon ERC-721 by batching multiple non-fungible tokens into a single contract, reducing transaction costs.
NFTs are created through a process called minting, in which the information of the NFT is recorded on a blockchain. At a high level, the minting process entails a new block being created, NFT information being validated by a validator, and the block being closed. This minting process often entails incorporating smart contracts that assign ownership and manage the transferability of the NFT.
As tokens are minted, they are assigned a unique identifier directly linked to one blockchain address. Each token has an owner, and the ownership information (i.e., the address in which the minted token resides) is publicly available. Even if 5,000 NFTs of the same exact item are minted (similar to general admission tickets to a movie), each token has a unique identifier and can be distinguished from the others.
Like physical money, cryptocurrencies are usually fungible from a financial perspective, meaning that they can be traded or exchanged, one for another. For example, one bitcoin is always equal in value to another bitcoin on a given exchange, similar to how every dollar bill of U.S. currency has an implicit exchange value of $1. This fungibility characteristic makes cryptocurrencies suitable as a secure medium of transaction in the digital economy.5
For this reason, NFTs shift the crypto paradigm by making each token unique and irreplaceable, making it impossible for one non-fungible token to be "equal" to another. They are digital representations of assets and have been likened to digital passports because each token contains a unique, non-transferable identity to distinguish it from other tokens. They are also extensible, meaning you can combine one NFT with another to create a third, unique NFT.
Non-fungible tokens are an evolution of the relatively simple concept of cryptocurrencies. Modern finance systems consist of sophisticated trading and loan systems for different asset types, from real estate to lending contracts to artwork. By enabling digital representations of assets, NFTs are a step forward in the reinvention of this infrastructure.