There's a good change that if you're active on social media, on Twitter, Instagram or Facebook, you'll have come across photos of your friends looking a lot older.

This is down to an app with an impressive AI facial recognition tool that processes images of faces, and then generates realistic, older versions of those faces, often including grey hair in impressive detail. 

What is FaceApp? 

FaceApp is a free app available on both the iOS App Store and the Google Play Store. That means, if you have an Android phone or an iPhone, you can use it. 

It's not a new app, it's been around for a little while now, but is primarily billed as an app to make your selfies better. It has a host of features designed to add design touches to your photos. 

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You can use it to add glasses, change your hair colour, style, makeup or smile, among many other features. Some of which are limited to premium in-app subscription purchases. You can even swap gender if you'd like to, similar to the feature baked into Snapchat's newest filters. 

What makes this app so unique, however, is that it's powered by what the developers call "advanced neural portrait editing technology". It's AI/Machine Learning trained specifically to recognise facial features, and the process changes to them, while retaining an impressively realistic look. 

In regards to the ageing filter, specifically, people have been having a lot of fun sharing this eerily realistic results on Twitter, Instagram and Facebook. 

How do I make myself look old? 

Because of the advanced neural processing engine, your part in using this app is very simple. First up: download the app on your phone. 

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When you first launch it, on both Android and iPhone it'll need permission to access your camera and your image gallery, so you'll need to approve those permissions. 

Once that's done, you'll see it automatically looks through your camera roll for faces, and loads them all up in a grid. This can take 30 seconds or so. As soon as that's done, the first square in this grid has a camera icon on it, tap this one to take a new selfie, or choose a pre-existing one. 

When you've shot a photo, or selected one from the gallery, it takes a few seconds to process the data and then takes you to the editing view where all the magic happens. 

Along the bottom of the screen, you'll see a row of different filter options. Choose "age", then "old" and wait for a few seconds as it processes the image, and then turns you into an old woman, or old man. 

To save it, hit "Apply" and then hit the little download arrow in the top corner to save it to your phone and share it on social media. 

Here's a selection of our finest Pocket-lint staffers, made to look much, much older. 

Quick fun tip: For an even more extremely aged look, try running the images of your older self through the process again. See what happens. 

Of course, if you want to, you can choose to have yourself made to look younger. In our experience however, these just look downright weird. 

So there you have it. It's not new, but for whatever reason, recently it's become something of a hit.  

What about privacy? 

So here's one part of the app making the headlines in not such a positive and fun way: part of the app's privacy terms essentially mean you're agreeing for FaceApp to use your photos anyway it wants to. Whether that's promotional material or otherwise, without being compensated. So just be sure to read through the terms before you sign up and give the app access to your photos. 

“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."

You can read more about the company's privacy policy at FaceApp.com/privacy