A non-fungible token (NFT) is a one-of-a-kind, non-transferable data unit kept on a blockchain, which is a type of digital ledger. NFTs can be linked to digital assets that can be reproduced, such as images, movies, and audio. NFTs use a digital ledger to offer a public certificate of authenticity or proof of ownership, but they leave the underlying digital files open to sharing and copying. NFTs are distinguished from blockchain cryptocurrencies like Bitcoin by their lack of interchangeability (fungibility).