How NFTs Work
๐ 7 min read
Quick Answer
Behind the hype, NFTs work through a few straightforward blockchain mechanics: a smart contract mints a unique token, records who owns it, and points to the item it represents. Understanding minting, metadata and where the image actually lives explains a lot, including why some NFTs quietly broke when the website hosting their picture went offline.
๐ผ๏ธ The mental model
An NFT is like a numbered certificate of authenticity in a public ledger. The certificate (the token) lives permanently on the blockchain and says who owns it. But the artwork it describes often hangs in a separate gallery (a server) somewhere, and if that gallery closes, the certificate still exists but may point at an empty wall.
Minting and smart contracts
An NFT is created ("minted") by a smart contract that issues a unique token with its own ID and records the owner on the blockchain. Most run on Ethereum or compatible chains using standards like ERC-721. The contract enforces that the token is unique and tracks every transfer, giving public, tamper-evident provenance.
Token standards
Standards make NFTs interoperable. ERC-721 defines a unique single token; ERC-1155 allows both unique and semi-fungible tokens (useful for game items). Because they follow shared standards, NFTs can be held in standard wallets and traded on marketplaces, the same plumbing the whole ecosystem relies on.
Metadata: where the image lives
The token usually does not store the image itself (too expensive on-chain). Instead it stores "metadata", a link to the image and details. If that link points to an ordinary web server and the server goes down, the NFT can lose its picture. This is why "on-chain" NFTs (storing data on the blockchain) or decentralized storage like IPFS matter for permanence.
Buying, selling and royalties
NFTs are traded on marketplaces where ownership transfers are recorded on-chain. Many include programmable royalties, paying the original creator a cut of future sales automatically, though enforcement has weakened over time. Every transfer is public, so anyone can verify an NFT's full history and current owner.
๐ Key takeaway
An NFT is minted by a smart contract that issues a unique token (often ERC-721) and records ownership and transfers on the blockchain. The image itself usually lives off-chain via metadata links, so permanence depends on decentralized storage like IPFS or true on-chain data. Trades and programmable royalties are recorded publicly, giving verifiable provenance.
Why this matters for you
As practical NFT uses (gaming, ticketing, loyalty) grow across Asia, understanding the mechanics, especially where the data actually lives, helps users and builders judge which NFTs are durable and which could vanish if a server disappears. It is the technical literacy needed to use the technology beyond speculation.
Frequently asked questions
What does "minting" an NFT mean?โผ
Creating it: a smart contract issues a new unique token with its own ID and records the first owner on the blockchain. From then on, every transfer of that token is tracked on-chain, giving public, verifiable ownership and history.
Is the image stored on the blockchain?โผ
Usually not, storing images on-chain is expensive. The NFT typically stores "metadata" linking to the image hosted elsewhere. If that link points to an ordinary server that goes offline, the NFT can lose its picture, which is why decentralized storage (IPFS) or fully on-chain NFTs matter.
What is ERC-721?โผ
The most common Ethereum token standard for NFTs, defining a unique, non-interchangeable token. Shared standards like ERC-721 (and ERC-1155 for game-style items) let NFTs work across standard wallets and marketplaces.
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๐ Sources & further reading
Authoritative references and primary sources used in this guide.