An NFT is a non-fungible token. A non-fungible token is a unique (non-interchangeable) unit of data stored on a blockchain, a form of digital ledger, that can be sold and traded. Types of NFT data units may be associated with digital files such as photos, videos, and audio.
NFTs are more involved than regular digital image files, because they are tied to a ledger that documents its entire history, and because they are overseen by a contract that can have real-world components.
In weed, NFT art became extremely popular starting in 2021.