<!---- What is an NFT? ---->
NFT (Non-fungible token) is a unique, non-interchangeable (non-fungible)
unit of data stored on a blockchain (such as the Ethereum blockchain).
Non-fungible means that an NFT cannot be traded with another NFT.
Currency is fungible, as you can exchange one dollar for another dollar,
but NFTs are like one-of-a-kind cards which cannot be exchanged.
"At a very high level, most NFTs are part of the Ethereum blockchain.
Ethereum is a cryptocurrency, like bitcoin or dogecoin, but its
blockchain also supports these NFTs, which store extra information
that makes them work differently from, say, an ETH coin. It is worth
noting that other blockchains can implement their own versions of NFTs."
<!---- What is an NFT? ---->