How NFT Metadata works

NFTs are a container for digital certification of objects representing the physical world or the metaverse. But how does metadata actually work? Where is it stored?

Non-fungible tokens are currently one of the most discussed topics in the Blockchain and cryptocurrency world. The functionality and use cases resulting from this implementation of Smart Contracts allows interactions with many areas in everyday life. Behind every token there is the concept of metadata, which describes the multimedia content of which the token is container and certifier. So how does metadata work? What is the standard that defines them?

The metadata of an NFT, whether developed according to the ERC721 or ERC1155 standard, is generally saved in the IPFS, a peer-to-peer protocol for saving multimedia files. This metadata is pinned (hence the “pinning” services such as Pinata) to the protocol and returned as a hash to the Smart Contract. The resulting url, in the form https://ipfs.io/ipfs/QmZ8epAYRBVgmC89AkhMcYTvSXqaXoVyY1wDejcts8YfrF?filename=metadata1.json, is saved in the Smart Contract storage and associated to the ID of the corresponding token.