NFTs, like cryptocurrencies, are transactions stored on the blockchain. However, what sets it apart from cryptocurrencies is its non-fungible feature. One bitcoin will always be equal to another bitcoin, we can exchange them for each other, and they all have the same value. It's the same with dollars: it's called the fungible property of money. The creators of NFT wanted to do exactly the opposite: a transaction stored on the blockchain that is non-fungible, therefore completely unique. The idea is to be able to use it as a certificate of authenticity associated with a digital or physical object.