The ERC721 token standard allows for the implementation of a standard API for NFTs within smart contracts. This standard provides basic functionality to track and transfer NFTs.
Use cases of NFTs being owned and transacted by individuals as well as consignment to third party brokers/wallets/auctioneers (“operators”). NFTs can represent ownership over digital or physical assets. Some examples of NFTs include:
Physical property — houses, unique artwork
Virtual collectables — unique pictures of kittens, collectable cards
“Negative value” assets — loans, burdens and other responsibilities