NFT Metadata is defined well in the Ethereum documentation that could be found on this address https://eips.ethereum.org/EIPS/eip-721. There are also several external places – platforms, services and companies that try to do something on it:
- NFT Guide: How To Read Metadata To Snipe Rare Traits – by Huhao – NFT Caviar (substack.com)
- Developer Quick-Start: NFTs and Metadata | Hedera
- https://editorial.mintable.app/2021/08/09/nft-metadata-whats-all-this/
Basically the Meta Data has the following fields:
- Non Fungible Token – Title
- Object Type
- Name
- Description
- Image (Address) – Preferably stored on the hash based system.
These are the required fields across all implementations. Few more properties that are needed for manipulation and storing are:
- Globally Unique Identifier of the Token
- GUID (or address on the hash based storage) of the Meta Data
- additional properties in different forms – most often in key-value format.
Many different blockchains offer storing NFT collectibles – with more and more features – beyond non-divisible ones. The Cardano Blockchain puts a Policy ruler – above the Tokens that may define how they behave. Some other layer 1 or layer 2 protocol – that try to merge the hashes into a single Ethereum transaction – may put another field
Accordingly the NFT properties may grow, but the basic are those above. They should be transferable, verifiable and owned by a crypto address – hopefully your own one. You know – not your keys, not your coins/tokens.