NFT (Non-Fungible Token): What It Is and How It Works

What "non-fungible" means

Something is fungible when every unit is interchangeable. One dollar bill is as good as another, and one bitcoin is worth the same as any other bitcoin. Most crypto tokens, including stablecoins, are fungible.

A non-fungible item is one of a kind: a painting, a concert seat with a specific row and number, a plot of land. An NFT brings that property on-chain. Each token carries a unique ID inside its smart contract, and the blockchain keeps a public record of which wallet address holds it and every transfer it has gone through. That record of past owners is called provenance.

How NFTs work

1. A contract defines the collection. A creator deploys a smart contract that follows an NFT standard. It sets rules such as how many tokens can exist and who can create them.
2. Minting. Creating a new token is called minting. The contract assigns it a token ID and records the minter's wallet as its first owner. Minting on Ethereum costs a network gas fee.
3. Metadata. Each token points to metadata: a name, a description, traits and a link to the image or file. Because storing large files on-chain is expensive, the media usually lives elsewhere, often on decentralized storage such as IPFS, and the token stores a link to it.
4. Trading and transfers. NFTs can be sent from wallet to wallet or sold on marketplaces. A sale is a smart-contract transaction that moves the token to the buyer and the payment to the seller.
5. Creator royalties. Many collections ask for a percentage of each resale to go to the creator. Whether it is paid depends on the marketplace, because the standard itself cannot force it.

The token proves control of a token ID, not of the file behind it. If the linked file is taken offline or changed, the NFT still exists but may point to nothing useful. Owning an NFT also does not, by itself, transfer the copyright of the artwork; any rights depend on the licence the creator attaches.

Royalties, a hypothetical example: an artist mints a work for 0.1 ETH and sets a 10% royalty on secondary sales. If it later resells for 1 ETH, 0.1 ETH goes to the artist, but only if the marketplace enforces the royalty; royalties are not guaranteed at the protocol level, and many marketplaces have made them optional.

Terms you will meet: the floor price is the cheapest listed item in a collection; provenance is the on-chain history of every transfer of an NFT, visible to anyone. NFTs trade on marketplaces such as OpenSea, Magic Eden and Blur.

NFT standards

On Bitcoin, Ordinals inscribe data directly onto individual satoshis, which gives a similar result without a smart contract.

A short history of NFTs

Early experiments with unique tokens appeared on Bitcoin through "colored coins" and on Counterparty. The idea took hold on Ethereum, where projects such as CryptoPunks, a set of pixel-art characters, and CryptoKitties, a game of collectible digital cats that at one point congested the network, showed that people would collect and trade unique tokens.

The ERC-721 standard gave these projects a shared format, so any wallet or marketplace could display and transfer any compliant NFT. A boom followed in which NFT art reached traditional auction houses, most famously a Christie's sale of a digital work by the artist Beeple, and profile-picture collections such as Bored Ape Yacht Club drew mainstream attention.

Trading volumes later fell sharply from their peak. Attention shifted toward practical uses: blockchain domain names such as ENS, game items, tickets, memberships and non-transferable soulbound tokens for credentials.

More milestones from that history:

• 2012: "Colored coins" experiments marked small amounts of bitcoin to represent other assets, an early precursor of NFTs.
• 2014: Kevin McCoy's "Quantum" is often cited as one of the first digital artworks registered on a blockchain.
• 11 March 2021: Beeple's (Mike Winkelmann's) "Everydays: The First 5000 Days" sold at Christie's for $69,346,250. Christie's described it as the first purely digital, NFT-based artwork offered by a major auction house; the sale pushed NFTs into mainstream news.
• 2021: Bored Ape Yacht Club, Art Blocks and NBA Top Shot drove the boom and showed NFTs reaching a mass-market audience.
• 2022 and after: trading volumes fell sharply, and attention shifted to functional uses: game items, ENS domain names, event tickets, and "soulbound" non-transferable tokens for identity and reputation, an idea Vitalik Buterin described in 2022.

What NFTs are used for

• Digital art and collectibles. Artists sell editions directly to collectors and can receive resale royalties where marketplaces honour them.
• Gaming. Items, characters and land in blockchain games can be owned by players and traded outside the game, as in Axie Infinity or The Sandbox.
• Domain names and identity. Names such as those from ENS map a readable name to a wallet address.
• Tickets and memberships. A token in a wallet can act as a pass to an event or a community.
• Real-world assets. Some projects use NFTs to represent a claim on a physical item or document, though the legal link to the item depends on off-chain agreements.
• Financial positions. Some DeFi protocols issue an NFT to represent a specific position, for example a concentrated liquidity pool deposit.

How NFTs are held

An NFT sits at a wallet address on its blockchain, and whoever controls that address's private key controls the token. A hot wallet is convenient for minting and trading. Valuable pieces are often kept in a hardware wallet, which signs transactions offline. Losing the seed phrase means losing access, and there is no issuer that can restore the token.

Risks of NFTs

• Illiquidity. A collection's lowest asking price, the floor price, can fall quickly, and some NFTs cannot be sold at any price.
• Scams. Fake collections copy popular ones, and malicious sites trick users into signing approvals that drain wallets. Blind signing a transaction you cannot read is a common way to lose NFTs.
• Broken links. If the media file is hosted on an ordinary server, it can disappear.
• Rights. Buying an NFT does not guarantee any copyright or commercial rights.
• Project risk. Teams can abandon a collection or its promised features; some projects are rug pulls.