The couple and their children were full of anticipation 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. Among the lots was a photograph of the youngest child - and the price kept going 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 sister Lily were sitting in the car, apparently on their way to school. Suddenly their mother, Katie, sprang a surprise on them: they were going to Disneyland. Lily was so delighted she burst into tears - prompting Chloe to give a sidelong glance.

When Katie posted the picture, it became a social media sensation. Not only was it shared millions of times, but people started producing memes of 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 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 excited about Disneyland.

But as Chloe explained a few years later, she was simply confused as to why her sister was crying.

In April, a meme called Disaster Girl sold for £365,000. It shows a little girl smiling against a background of a burning house. The house was empty and had been set on fire 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 is much higher. Doge, a picture of a dog, went for almost £3m.

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 - rather like owning the typescript of a novel.

NFTs have started to have a major impact. 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. bought a Banksy print and then burnt it - after creating an NFT which they then sold for £274,000.

Sceptics 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 a former Christie's auctioneer. "I think people who invest in it are slight mugs."

No. Real works of art have a serious side and prompt important questions; most memes are just jokes. Art demands a high degree of technical expertise. It is ridiculous that a meme should sell for as much as a centuries-old painting which has stood the test of time.   

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