FaceApp is provoking a combination of delight and repulsion among the huge number of people using it to turn themselves and others older.

The app uses artificial intelligence to change your photos – changing it so that users look young or older, or swapping their genders, for instance.

But the terms of the Russian-owned app have led to a number of warnings about what it could actually be doing with your photos.

When users submit a photo to the app to change how it looks, it makes its way onto FaceApp’s servers. And it is not entirely clear what is happening when it does.

FaceApp has to select and upload the users’ photo to ensure that it can be altered. The changes use FaceApp’s artificial intelligence tools, which run on its servers, and so the photo must make be given over to the app.

10 of the best celebrity FaceApp Challenge photos Show all 10 1 /10 10 of the best celebrity FaceApp Challenge photos 10 of the best celebrity FaceApp Challenge photos Drake Canadian rapper Drake used the FaceApp filter on a photograph of him wearing a grey overcoat, roll neck and silver chain necklace. In the caption, Drake offered fans tickets to his music festival for the best picture caption on his post which has since been liked by more than 1.6m people. 10 of the best celebrity FaceApp Challenge photos The Jonas Brothers The Jonas Brothers’ official Instagram account shared a picture of Kevin, Joe and Nick looking quite a few years older older. In the caption, the band referenced a Busted song they previously covered, writing: “When you take a trip to the Year 3000.” 10 of the best celebrity FaceApp Challenge photos Sam Smith British singer Sam Smith posted a photograph of himself wearing sparkly heart-shaped earrings while sporting a bushy white beard. “Grandpa or Grandma? I’Il take both #batch,” Smith wrote in the caption. 10 of the best celebrity FaceApp Challenge photos Piers Morgan Good Morning Britain host Piers Morgan applied the FaceApp filter to an image of himself wearing a blue suit and tie. He simply wrote alongside the picture: “I need a break.” 10 of the best celebrity FaceApp Challenge photos Gordon Ramsay British chef Gordon Ramsay used the FaceApp filter on a photograph of himself starring in the American version of Masterchef. “Me doing a demo on #MasterChef Season 50....” he wrote in the caption. 10 of the best celebrity FaceApp Challenge photos David Guetta French DJ and producer David Guetta shared an aged bathtub selfie on Instagram, writing: “Back from my show in Ibiza I've been a DJ for 60 years and I still love it. July 15 2040.” 10 of the best celebrity FaceApp Challenge photos Marvin and Rochelle Humes Husband and wife presenting duo Marvin and Rochelle Humes added the FaceApp filter to a photograph of themselves while sunbathing on holiday. While Rochelle’s face remained fairly unedited, Marvin was given whispy white hair and a grey beard. “Roch and her Sugar Daddy” the photograph was captioned. 10 of the best celebrity FaceApp Challenge photos Scooter Braun Music industry manager Scooter Braun referenced his recent controversy with singer Taylor Swift in his FaceApp post, writing: “Last couple of weeks have really taken a toll on me.” 10 of the best celebrity FaceApp Challenge photos Ludacris American rapper Ludacris posted a selfie of himself and Fast & Furious co-star Tyrese, writing: “Fast & Furious 50 and we still haven’t stopped at a gas station. Or for Diapers.” 10 of the best celebrity FaceApp Challenge photos Lil Nas X American singer and rapper Lil Nas X shared his aged selfie on Instagram alongside the caption: “Feeling cute might delete later.”

But you might be giving over more than you realise. Numerous people have pointed to the fact that those photos can be used by FaceApp – and not just to make you look different.

The terms give the app the ability to use those photos in just about any way, without giving anything back to the users who first created them, the app makes clear.

“You grant FaceApp a perpetual, irrevocable, nonexclusive, royalty-free, worldwide, fully-paid, transferable sub-licensable license to use, reproduce, modify, adapt, publish, translate, create derivative works from, distribute, publicly perform and display your User Content and any name, username or likeness provided in connection with your User Content in all media formats and channels now known or later developed, without compensation to you,” its terms read.

In practise that means that the photos you upload into the app might seem initially private, but that they could be used in very public ways later on.

Similarly, the company’s privacy policy makes clear that it is able to collect and store information from your phone and that it might be used for ads or other forms of marketing.

Such terms are fairly standard within such apps, and it is required that such an app will have some access to photos to fulfil its functions. But the fact that so little is known about the app, and that it is made by developers in Russia, have led some to warn that it is best not to use it, or to be careful when doing so.

Some have also expressed concern about the fact that the app appears to have access to all of your photos when it lets you choose which you want to adjust. A very viral tweet claimed that as soon as users open the app, photos start being uploaded onto the internet.

But on iOS, the app actually takes advantage of a feature inside the iPhone’s software: though all of your photos will come up as options, the picture won’t actually be handed over to the app until you’ve chosen which you want, and all of the others will remain hidden. Privacy researchers digging into the hidden parts of the app have claimed there is nothing to indicate that the app is taking all of a user’s images.

The app itself is old and so are the warnings: many of these features were first discussed when the app first made its appearance in 2017. But despite feature updates and other changes, the fundamental thrust of the way the app uses those photos does not appear to have changed.