Cryptocurrencies, utility tokens, security tokens, privacy tokens… digital assets and their classifications are multiplying and evolving right alongside cryptographic and blockchain technology.

Non-fungible tokens (NFTs) are one of the fastest-growing sectors in the crypto industry. In this guide, we explore what they are, how they work, and how they're being used.

Non-fungible tokens are digital assets that contain identifying information recorded in smart contracts.

It’s this information that makes each NFT unique, and as such, they cannot be directly replaced by another token. They cannot be swapped like for like, as no two NFTs are alike. Banknotes, in contrast, can be simply exchanged one for another; if they hold the same value, there is no difference to the holder between, say, one dollar bill and another.

Bitcoin is a fungible token. You can send someone one Bitcoin and they can send one back, and you still have one Bitcoin. (Of course, the value of Bitcoin might change during the time of exchange.) You can also send or receive smaller amounts of one Bitcoin, measured in satoshis (think of satoshis as cents of a Bitcoin), since fungible tokens are divisible.

Typically, non-fungible tokens are not divisible, in the same way that you cannot send someone part of a concert ticket; part of a concert ticket wouldn’t be worth anything on its own and would not be redeemable. However, in recent months some investors have experimented with the concept of fractionalized NFTs, though they remain a legal grey area and could be seen as securities.

CryptoKitties collectibles were some of the first non-fungible tokens. Each blockchain-based digital kitten is unique; if you send someone a CryptoKitty and receive a CryptoKitty from someone else, the one you receive will be a completely different CryptoKitty from the one you sent. Collecting different digital kittens is the point of the game.