The couple and their two children were full of anticipation as they huddled in front of the computer in their UtahA mountainous state in the west of the USA. More than half its inhabitants are Mormons, who founded its capital, Salt Lake City. home. They were watching an auction - but not a traditional one. Among the lots was a photograph of the youngest child - and the price kept going up and up. By the time the bidding finished they were 25 EtherA crypto-currency produced by the Ethereum blockchain. richer: enough to pay the family food billThe average American family spends ,120 (£820) per month on food. for five and a half years.

The photo was taken eight years ago, when Chloe and her older sister Lily were sitting in the family car, apparently on their way to school. Suddenly their mother, Katie, sprang a surprise on them: they were actually going to Disneyland. Lily, then aged eight, was so delighted that she burst into tears - prompting Chloe to give a sidelong glance.

When Katie posted the picture on the internet, it became a social media sensation. Not only was it shared millions of times, but people started producing other memes based on it. Chloe's face appeared on T-shirts and was featured in a Google advertisement in Brazil. She now has more than 500,000 Instagram followers.     

What makes the meme's success even stranger is that many people completely misread it. Caroline Anders of the Washington Post describes Chloe's expression as "disapproving, sassyCheeky, full of character. and a bit concerned. Overall unimpressed" - as if she is not in the least excited about going to Disneyland.

But as Chloe explained in an interview a few years later, she was not thinking that at all - she was simply confused as to why her sister was crying.

Side-Eying Chloe is not the only meme to go for a huge sum: in April, one called Disaster Girl sold for £365,000. It shows a little girl smiling against a background of a burning house, as if she were enjoying a tragedy. In fact, the house was empty and had been set on fire deliberately to provide practice for the emergency services.

Another meme, Overly Attached Girlfriend, fetched £300,000. All three were bought by a music production company called 3F.

The record price, though, is much higher. Doge, a picture of a dog, went for almost £3m in June.

The sales have been made possible by the creation of non-fungibleImpossible to replace with something similar. tokens, or NFTs; digital versions of images which only one person can own, even though multiple copies might exist - rather like owning the typescript of a novel.

NFTs have started to have a major impact on the art world. In February, a collage of 5,000 images by BeepleAn American graphic designer whose real name is Mike Winkelmann. His collage consists of images made at a rate of one a day for 13 years. sold for £50m, making him one of the three most valuable artists in the world, according to Christie'sOne of the two biggest art auction houses in the world, along with Sotheby's. Originally based in London, it now has branches across the world. .  

One consortiumA group of people. It derives from two Latin words meaning share and destiny. even bought a Banksy print and then burnt it - after creating an NFT which they then sold for £274,000.

Sceptics, however, question whether NFTs are more than fads, and whether memes constitute art. "The idea of buying something which isn't there is just strange," says Charles Allsop, a former Christie's auctioneer. "I think people who invest in it are slight mugs."

Some say, no. Real works of art have a serious side to them, even if they take the form of comedy, and prompt important questions; most memes are just silly jokes. Art also demands a high degree of technical expertise, which cannot be said of an image taken from an amateur video. It is ridiculous that a meme should sell for as much as a centuries-old painting which has stood the test of time.   

Others argue that art is a reflection of the society that produces it - and since we now live in a digital world, it is only right that a meme which has engaged millions of people should be considered valuable. Andy Warhol's pictures of soup cans were widely ridiculed when he painted them, but have come to be seen as important comments on consumer culture and now fetch enormous prices.