The ownership rights of an NFT (Non-Fungible Token) are defined by the smart contract that governs the NFT. This smart contract is a blockchain-based digital ledger that records the unique identifier of the NFT and the ownership of the NFT. The smart contract also includes the terms and conditions of the ownership rights, such as the transferability of the NFT, the reproduction rights, and the use of the NFT. Once the NFT is minted or created, the smart contract is deployed on the blockchain, and ownership of the NFT becomes recorded on the blockchain. This means that the ownership of the NFT is secure, transparent, and tamper-proof. Furthermore, the blockchain-based smart contract ensures that ownership of the NFT can only be transferred if the criteria for transfer, such as an agreed price or specific conditions, are met.