non-fungible-tokens-(nfts)
NFTは、アート、音楽、または収集品などのアイテムの所有権を表す、ブロックチェーンに保存されたユニークで代替不可能なデジタル資産です。
Non-Fungible Tokens (NFTs) are unique digital assets whose ownership is recorded on a blockchain. Unlike cryptocurrencies like Bitcoin, where each unit is identical and interchangeable (fungible), each NFT is distinct and cannot be replaced one-for-one. NFTs are created ('minted') using smart contracts on various blockchains, most commonly Ethereum, Solana, Polygon, and Flow. The smart contract assigns a unique token ID and associated metadata to the NFT. This metadata typically includes a link to the digital item (e.g., artwork, music file, video clip, virtual land deed) and descriptive information. The blockchain acts as a decentralized, immutable ledger, verifying the authenticity and ownership history of the NFT. This allows for verifiable digital scarcity, enabling creators to sell unique digital items and collectors to prove ownership. Common NFT standards include ERC-721 (for unique items) and ERC-1155 (for multiple copies of items) on Ethereum. The value of an NFT is derived from its uniqueness, provenance, utility (e.g., in games or metaverses), and market demand. Trade-offs involve the environmental impact of some blockchains (e.g., Proof-of-Work Ethereum prior to the Merge), the volatility of the NFT market, and the reliance on external storage (like IPFS) for the actual digital asset, which can pose risks if the storage fails.
graph LR
Center["non-fungible-tokens-(nfts)"]:::main
Pre_cryptography["cryptography"]:::pre --> Center
click Pre_cryptography "/terms/cryptography"
Rel_smart_contracts["smart-contracts"]:::related -.-> Center
click Rel_smart_contracts "/terms/smart-contracts"
Rel_nft["nft"]:::related -.-> Center
click Rel_nft "/terms/nft"
Rel_erc_721["erc-721"]:::related -.-> Center
click Rel_erc_721 "/terms/erc-721"
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🧠 理解度チェック
🧒 5歳でもわかるように説明
NFTs are like digital collector's items, such as a unique [trading](/ja/terms/trading) card or a one-of-a-kind painting, but they live on a computer network ([blockchain](/ja/terms/blockchain)) so everyone can see who owns them.
🤓 Expert Deep Dive
NFT smart contracts, often following ERC-721 or ERC-1155 standards, manage ownership mapping (owner address to token ID) and metadata URIs. The metadata itself is frequently stored using decentralized storage solutions like IPFS or Arweave to ensure greater resilience than centralized servers, though the link's integrity remains a critical factor. The 'non-fungible' property is enforced by the uniqueness of the tokenId within a given contract and the distinct metadata associated with each token. Smart contract vulnerabilities (e.g., reentrancy attacks, access control flaws) can compromise token security and transferability. Architectural choices involve selecting the blockchain platform (considering transaction fees, speed, and security), the metadata standard, and the storage solution. The concept of 'ownership' is tied to control of the private key associated with the blockchain address holding the NFT, not necessarily copyright or intellectual property rights unless explicitly defined.