What is NFT metadata?
- Author
- CRYPTO PORT Editorial
- Published
- Updated
- Reading time
- 5 min
In short
Metadata is the record that gives an NFT its name, image and traits. Most NFTs store only a URI on chain and keep the content elsewhere, so if that location disappears the artwork stops resolving. Where the data lives is therefore worth checking.
Key points
- Usually a JSON file with name, image URL and traits
- Often only the URI itself is stored on chain
- If the target goes offline, the NFT stops rendering
- Some contracts let the issuer swap it after minting
Definition
The data that defines what an NFT shows. In ERC-721 and similar standards, the tokenURI points to a JSON document holding the name, description, image location and traits.
An ERC-721 contract exposes a tokenURI function that returns a string for a given token ID. That string is usually an https:// or ipfs:// URI pointing at a JSON document, and marketplaces and wallets read it to render the image and traits.
So what the chain guarantees is who holds which token ID, and where that ID points. The image itself sits elsewhere. If that elsewhere is an ordinary web server, the NFT stops resolving the day the team drops the domain. A content-addressed system like IPFS guarantees the bytes cannot change, but someone still has to keep hosting them.
Contracts that can change the tokenURI later are common too. That is how a 'reveal' works — a placeholder before the sale ends, the real art afterwards — but the same mechanism can replace the content at any time. Reading the contract shows who holds that permission.
Watch out for
- · When the image is off chain, owning the NFT does not mean owning a stored copy
- · If the issuer can change the tokenURI, what you see can change after you buy
- · Marketplace previews are cached by each site and do not prove the source still exists