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<aside> đź’ˇ Non-fungible tokens (NFTs) are unique, digital items with blockchain-managed ownership. Examples include collectibles, game items, digital art, event tickets, domain names, and even ownership records for physical assets.
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Most discussions about non-fungible tokens begin by introducing the idea of fungibility, which is defined as “able to replace or be replaced by another identical item”. We think this overcomplicates things. To get a better sense of what might constitute a non-fungible asset, just think about most of the stuff you own. The chair you’re sitting in, your phone, your laptop, anything you could go and sell on eBay. All of these fall under the category of non-fungible things.
It turns out that fungible assets are actually the odd ones out. A currency is a classic example of a fungible asset. Five dollars is always five dollars no matter the serial number on the specific five-dollar bill, or whether its five dollars sitting in your bank account. The ability to replace a five-dollar bill with another five-dollar bill (or five ones, for that matter) is what makes currency fungible.
Note that fungibility is relative; it really only applies when comparing multiple things. Consider business class, economy class, and first-class flight tickets. Each ticket is roughly fungible within its class, but you couldn’t fairly swap a first-class ticket for a business class ticket. Even the chair you’re sitting in is roughly fungible with a chair of the same model, unless you’ve developed a special attachment to your particular chair.
Interestingly, fungibility can also be subjective. Back to the flight ticket example: a person that cares about sitting in a window seat vs. an aisle seat might not consider two economy class tickets interchangeable. Similarly, a rare penny might be worth 1 cent to me but worth much more to a coin collector. We’ll see that some of these nuances become important when representing these items on blockchains.
Just as we had digital currencies (think airline points, in-game currencies) before cryptocurrencies emerged, we’ve had non-fungible digital assets since the dawn of the internet. Domain names, event tickets, in-game items, even handles on social networks like Twitter or Facebook, are all non-fungible digital assets; they just vary in their tradeability, liquidity, and interoperability. And many of them are incredibly valuable: Epic Games made $2.4 billion in revenue selling costumes in their free-to-play game Fortnite in 2018 alone, the market for event tickets is projected to reach $68 billion in 2025, and the market for domain names continues to see solid growth.
We have tons of digital stuff, we’ve just never really owned it.
So it’s clear we already have tons of digital stuff. But to what extent do we “own” these digital things? If digital ownership only means that an item belongs to you and not someone else, then you own them in some sense. But if digital ownership is more like ownership in the physical world (the freedom to hold and transfer indefinitely), this doesn’t always seem to be the case with digital assets. Rather, you own these assets in specific contexts, which may or may not make moving them around easy. Try to sell a Fortnite skin on eBay, and you’ll discover the difficulty of moving digital assets from one person to another.
This is where blockchains come in! Blockchains provide a coordination layer for digital assets, giving users ownership and management permission. Blockchains add several unique properties to non-fungible assets that change the user and developer relationships with these assets.