NFT is short for non-fungible token. To put it short, it is a bit of data that is one-of-a-kind and stored on a blockchain. It is a different thing from cryptocurrencies, because each NFT is distinguishable from each other while each, for example bitcoin, is equal. NFTs are used as digital signatures to pictures, including pieces of digital art. People who support the idea of NFT claim that it is a proof of ownership of certain piece of digital media, though law doesn't say anything about that. Making a picture into NFT also don't prevent anyone from saving and using an image. At some point appeared also NFT collections which basically are collections of generated images, each one a slight variation of a base picture, each one with assigned NFT signature, sold at price counted in cryptocurrency. Most notable example of such NFT collection is Bored Ape Yacht Club. Curently owners of those ape NFTs are reselling them for price that sometimes even counts in milions of dollars for the most rare apes.