Non-fungible tokens (NFTs) are indivisible and one-of-a-kind cryptocurrency tokens. One NFT cannot be replaced with another, and the whole cannot be disassembled and used separately. NFTs have a wide range of opportunities for creating and selling digital objects, including original artwork and blockchain-based collectible games like CryptoKitties. NFTs may be used to show the rarity and provenance of both digital and physical properties. The ERC-721 token specification is primarily used to create non-fungible tokens on Ethereum.