• In economics, a fungible asset is like money - it is something with units that can be interchanged. With money, a $10 can be exchanged for two $5, and it still has the same value.
• If something is non-fungible, it has unique properties and cannot be interchanged with something else, such as a house, the Mona Lisa painting, etc.
• NFTs are distinct assets in the digital world. They can be bought and sold like any other property, but they have no tangible form.
• The digital tokens are like certificates of ownership for virtual or physical assets.

Traditional art is valuable because they are unique. But digital files can be duplicated.

With NFTs, artwork can be "tokenised" - a digital certificate of ownership that can be bought and sold. A record of who owns what is stored on a shared ledger known as a blockchain.

Nothing is stopping people from copying digital art. But the buyer of the NFT owns a "token" that proves they own the "original" work.

People are paying millions of dollars for tokens.

• On 19 February, an animated Gif of Nyan Cat sold for over $500,000.
• Weeks later, musician Grimes sold some of her digital art for over $6m.
• Twitter's founder promoted an NFT of the first-ever tweet. Bids are hitting $2.5m.
• Christie sold an NFT by digital artist Beeple for $69m.

Beeple (Mike Winkelmann) thinks there will be a bubble.

People selling the NFTs are "crypto-grifters", David Gerard, author of Attack of the 50-foot Blockchain, said. While some artists are doing great on this stuff, most people probably won't.