NFTs and Tokens
Unique digital assets on the blockchain
Definition
A Non-Fungible Token (NFT) is a unique digital identifier recorded on a blockchain that certifies ownership and authenticity of a specific digital or physical asset. Unlike cryptocurrencies (which are Fungible — one Bitcoin is interchangeable with another), each NFT is unique and cannot be exchanged on a one-to-one basis. NFT use blockchain smart contracts to track ownership, enable transfers, and enforce creator Royalty. Key concepts include IPFS.
Fungibility is the key concept. A dollar bill is Fungible — any dollar is as good as any other. A concert ticket is non-fungible — your seat is unique, and another ticket is for a different seat. NFT bring this concept to digital assets. An NFT's smart contract assigns a unique token ID to each asset, stores Metadata (name, description, image link), and records ownership on the blockchain. Standards like ERC-721 (for individual NFT) and ERC-1155 (for both Fungible and non-fungible tokens) define how NFT work on Ethereum.
Real-Life Example
Think of an NFT like a digital certificate of authenticity for a collectible. If you buy a rare baseball card, you get a certificate that proves it is authentic and you are the owner. Even though anyone can take a photo of the card, only you own the original. NFT work the same way digitally — anyone can view or download an NFT's image, but only the owner's blockchain address is recorded as the official owner. This creates digital scarcity, which was impossible before blockchain.
A practical example: Nike sells virtual shoes as NFT under their RTFKT brand. Someone buys a virtual sneaker NFT. They can use it as an avatar in games, trade it on marketplaces, and when Nike releases a physical version, the NFT owner gets first access to buy the real shoes. The NFT acts as both a digital collectible and a utility token — proving membership in an exclusive community and granting real-world benefits that a simple image download cannot provide.
Interactive Diagram
Launch the interactive diagram to see this in action.
Open Interactive DiagramThe interactive diagram for this chapter demonstrates Why Blockchain Is Secure. It shows different attack scenarios and how blockchain security features prevent them.
What to explore:
- try to tamper with a block; watch the chain become invalid; try a 51% attack; see the difficulty of compromising the network
- blockchain is secure because of cryptographic linking, distributed consensus, and the enormous computational cost of tampering
Introduction
When you buy a concert ticket, you own a unique seat. No one else can use that seat. But if you buy a digital image online, you can copy it infinitely and share it with everyone. Digital items have traditionally been copyable, which made digital ownership meaningless. Non-Fungible Tokens (NFT) change this by using blockchain to prove ownership of unique digital assets.
'Fungible' means interchangeable. One dollar is Fungible — any dollar is worth the same as any other dollar. One Bitcoin is Fungible — every BTC is identical. 'Non-fungible' means unique and not interchangeable. A one-of-a-kind trading card, a signed jersey, or a ticket to a specific concert are non-fungible. NFT are blockchain tokens that represent ownership of unique items — digital or physical.
In this chapter, you will learn what NFT and tokens are, how they work on the blockchain, and the various ways they are used. By the end, you will understand the concept of digital ownership and the opportunities and controversies surrounding NFT.
How It Works
An NFT is a smart contract that follows a specific standard (like ERC-721 or ERC-1155 on Ethereum). Each NFT has a unique token ID and Metadata that describes what it represents — this could be an image URL, a video link, a game item, or any digital or physical asset. The smart contract tracks who owns each token ID. Ownership is recorded on the blockchain and cannot be disputed.
To create (Mint) an NFT, you deploy a smart contract or call an existing contract's Mint function. You specify the token's Metadata (name, description, image link) and pay the gas fee. The contract assigns the token to your address. To transfer an NFT, you create a transaction calling the contract's transfer function. The contract updates the ownership record on the blockchain. Anyone can verify current ownership by reading the contract state.
Household Object Analogy
Think of NFT like certificates of authenticity for digital items. If you buy a painting from a gallery, you get a certificate that proves it is the original and authentic piece. Even though anyone can print a photo of the painting, the certificate proves you own the original. NFT serve the same purpose digitally — they certify that you own the original token, even though anyone can copy the associated image file.
Deeper Dive
NFT are used for digital art and collectibles. The most famous example is CryptoPunks — 10,000 unique pixel-art characters on the Ethereum blockchain, launched in 2017. Some CryptoPunks have sold for millions of dollars. Bored Ape Yacht Club, another popular NFT collection, grants membership to a community in addition to art ownership. The value of these NFT comes from scarcity, community, and speculation, similar to the market for physical art and collectibles.
Beyond art, NFT have practical applications. In gaming, NFT represent in-game assets (skins, weapons, land) that players truly own — they can trade them on open marketplaces, use them across different games (interoperability), or sell them when they are done playing. In ticketing, NFT prevent counterfeiting and allow resale Royalty to the original issuer. In real estate and supply chain, NFT can represent ownership of physical assets with the blockchain providing a tamper-proof record of provenance.
The environmental impact of NFT is often discussed. Ethereum's transition to Proof of Stake reduced its energy consumption by 99.95%, making NFT on Ethereum far more energy-efficient. Many NFT projects also use carbon offsets or choose energy-efficient blockchains like Solana or Tezos. The energy debate is largely a legacy concern following the Ethereum Merge.
Fungible tokens (as opposed to NFT) are interchangeable tokens that follow the ERC-20 standard. These represent currencies (USDC, DAI), utility tokens (UNI for Uniswap governance), and reward points. Unlike NFT, each unit is identical and any unit can replace any other unit. Both Fungible and non-fungible tokens are created and managed by smart contracts on blockchain platforms.
Key Insight
The concept of 'fungibility' comes from economics and law. A Fungible good is one where individual units are interchangeable — one barrel of oil is as good as another. A non-fungible good is unique — a specific house, a specific painting, a specific baseball card. NFT bring this economic concept to the digital world.
Advanced
NFT Royalty are a revolutionary feature. When an NFT is created, the creator can set a Royalty percentage (e.g., 10%). Every time the NFT is resold on a marketplace that respects Royalty, the creator automatically receives that percentage of the sale price. This is enforced by smart contracts and enables artists to earn ongoing income from secondary sales — something impossible with physical art or traditional digital sales.
NFT fractionalization allows multiple people to own shares of a single expensive NFT. A smart contract splits ownership into Fungible ERC-20 tokens, each representing a fraction of the NFT. Anyone can buy or sell fractions. This democratizes access to high-value assets and creates liquidity for otherwise illiquid NFT. Fractionalization has been used for assets like the ConstitutionDAO (which tried to buy an original copy of the US Constitution).
Dynamic NFT (dNFTs) can change their Metadata based on external conditions. For example, a game item NFT might level up based on how much the owner plays. A real estate NFT might update to show the current owner. Dynamic NFT use oracles to receive external data and update the token's Metadata accordingly. This opens possibilities for living digital assets that evolve over time.
Vocabulary Table
| Term | Definition |
|---|---|
| NFT | Non-Fungible Token — a unique digital asset verified on the blockchain. |
| Fungible | Interchangeable with other identical units, like currency. |
| ERC-20 | The standard for fungible tokens on Ethereum. |
| ERC-721 | The standard for non-fungible tokens on Ethereum. |
| Metadata | Data that describes the token, such as its name, image, and attributes. |
| IPFS | InterPlanetary File System — a decentralized storage network for NFT assets. |
| Mint | The process of creating a new token on the blockchain. |
| Royalty | A percentage paid to the original creator each time an NFT is resold. |
Fun Facts
The most expensive NFT ever sold is 'The Merge' by artist Pak, which sold for $91.8 million in December 2021. It was a 'mass' NFT where buyers purchased individual units that merged together.
The ERC-721 standard was proposed in January 2018 by Dieter Shirley, CTO of the CryptoKitties team. CryptoKitties was the first mainstream NFT application, launching in 2017.
Total NFT trading volume exceeded $40 billion in 2021 and 2022 combined, though volumes declined significantly during the 2022-2023 crypto bear market.
Major brands including Nike (virtual shoes), Adidas, Gucci, Starbucks (loyalty program), and the NBA (Top Shot) have launched NFT initiatives.
The 'NFT' term was first used in the Ethereum community and is not trademarked — anyone can call their token an NFT, though the technical standard (ERC-721) is specific to Ethereum.
Common Misconceptions
Misconception: NFT are just images you can right-click and save.
Truth: An NFT is a blockchain token proving ownership, not the image itself. Buying an NFT is like buying a signed print — anyone can take a photo of it, but only the owner has the verified original.
Misconception: All NFT are worth a lot of money.
Truth: Most NFT are worth very little or nothing. Like any collectible market, value depends on demand, scarcity, and community. Most NFT projects fail and become worthless.
Misconception: NFT are a scam or bubble.
Truth: While there have been scams and speculative manias in the NFT space, the underlying technology — provable digital ownership — has legitimate applications in gaming, ticketing, identity, and supply chain.
Misconception: You cannot use an NFT for anything practical.
Truth: NFT have practical uses: in-game asset ownership, event tickets with automatic Royalty enforcement, proof of authenticity for physical goods, membership passes, and decentralized identity credentials.
Knowledge Check
1. What makes a token "non-fungible"?
Answer: Each token is unique and cannot be exchanged one-to-one with another
2. What standard do most NFTs on Ethereum use?
Answer: ERC-721
3. What is a royalty in the context of NFTs?
Answer: A percentage paid to the creator each time the NFT is resold