A non-fungible token (NFT) is a non-interchangeable unit of data stored on a blockchain, a form of digital ledger. NFTs can also be associated with reproducible digital files such as photos, videos, and audio. NFTs use a digital ledger to provide a public certificate of authenticity or proof of ownership, but do not restrict the sharing or copying of the underlying digital files or the re-creation of identical NFTs. The ownership that NFTs confer is not legally binding. The lack of interchangeability (fungibility) distinguishes NFTs from blockchain cryptocurrencies, such as Bitcoin.