NFT (Non-Fungible Token) is literally a ‘non-fungible token’. Cryptocurrency, like real money, can be used by anyone and can be replaced, but NFTs have non-fungible characteristics because each digital asset has a unique recognition value. Due to the nature of blockchain technology, these NFTs cannot be deleted or forged once created, and ownership and transaction history are specified, so they can be used as a kind of 'digital certificate and proof of ownership'. Digital items can be easily copied without restrictions. Therefore, until now, it was not clear which was the original and who owned it. However, when an NFT is created, authentication and proof of ownership of the digital item are performed, so it becomes a ‘digital asset’ and can be freely bought and sold between people who want to trade.