GLOSSARY · BLOCKCHAIN & WEB3
NFT metadata
Additional information that describes the characteristics of an NFT, such as a name, image, description, or unique attributes.
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What is NFT metadata?
NFT metadata are data structures, usually in JSON format, which contain all the descriptive information associated with a non-fungible token.
This metadata is not part of the contract code, but is essential to represent the content, identity and properties of the NFT.
The most common fields include:
Name(token name)Description(description of its purpose or story)Image(URL of the image or multimedia content)Attributes(a list of characteristics such as rarity, color, level, etc.)external_urlor custom properties
The tokenURI() function in ERC-721 or ERC-1155 contracts is used to link each tokenId with its corresponding metadata.
This metadata may be stored on-chain (within the blockchain itself, although with space and cost limitations) or off-chain, in decentralized solutions such as IPFS (InterPlanetary File System), Arweave or even centralized servers in less sophisticated collections. Marketplaces such as OpenSea, LooksRare or Blur read this metadata to display NFTs visually, sort them by rarity, or filter by attributes.
In addition, they are essential in gamified environments, metaverses or utility projects, since they allow each token to be linked to functions, levels, statistics or access.
Poor management of metadata (for example, metadata that can be modified without control or that depends on a centralized server) can compromise the trust, value and permanence of an NFT.
Therefore, good practices include the use of immutable content hashes (CID), validated JSON structure, and decentralized storage.
In short, metadata gives an NFT meaning and visual, narrative and functional value, and is as important as the token itself in the Web3 experience.
Learn more: What are smart contracts and what are they used for?
Explained simply
An NFT's metadata is like its digital ID card.
It states its name, what image it has, what makes it special, what level of rarity it has or what collection it belongs to.
It is the information that makes an NFT not just a number, but something with its own identity, value and characteristics that distinguish it from others.
NFT metadata: key points
- They are descriptions in JSON that define the identity of the NFT
- They include name, image, attributes and other custom data
- They are linked using the contract's
tokenURI()function - They can be stored on-chain or in decentralized systems such as IPFS
- Essential for the visualization, utility and perceived value of the NFT
NFT metadata: advantages
- They allow full customization: each NFT can have unique properties
- They describe essential attributes for use in games, art, metaverse or collections
- Visibility in marketplaces: Metadata determines how the NFT is displayed
- Compatibility with standards ERC-721 and ERC-1155
- They promote gamification and scarcity, by allowing levels, rarities and stats
NFT metadata: disadvantages
- Risks if they are modifiable or hosted on centralized servers
- Dependency on external storage when they are not on-chain
- Lack of universal standards in cross-platform custom attributes
- Possibility of malicious or erroneous metadata, affecting the display or value
- High cost if you decide to store them fully on-chain
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