NFTs are used to represent ownership of unique items. They let us tokenize things like art, collectibles, even real estate. They can only have one official owner at a time, and they're secured by the Ethereum blockchain – no one can modify the record of ownership or copy/paste a new NFT into existence. NFT stands for non-fungible token. These things are not interchangeable for other items because they have unique properties. Fungible items, on the other hand, can be exchanged because their value defines them rather than their unique properties. For example, ETH or dollars are fungible because 1 ETH / $1 USD is exchangeable for another 1 ETH / $1 USD.