S ide-eying Chloe" Clem - a young girl who became an internet sensation when a picture of her looking unimpressed went viral - is selling the original image for thousands of dollars at auction. It's being offered as a "non-fungible token" (NFT), a way of owning the original digital image. Where Bitcoin was hailed as the digital answer to currency, NFTs are now being touted as the digital answer to collectables, but plenty of sceptics fear they're a bubble waiting to burst. What is a non-fungible token? In economics, a fungible asset is something with units that can be readily interchanged - like money. With money, you can swap a £10 note for two £5 notes and it will have the same value. However, if something is non-fungible, this is impossible - it means it has unique properties so it can't be interchanged with something else. It could be a house, or a painting such as the Mona Lisa, which is one of a kind. You can take a photo of the painting or buy a print