What is FaceApp, and how do you use it?

Its name is FaceApp, and if you're on Facebook, Twitter or Instagram, then chances are it's already starting popping up on your feed.

FaceApp is a free-to-download neural face transformation service which allows you to drastically alter your selfies using neural networks. There’s a filter which makes you look older, one that makes you look like a child, and another that will swap your gender.

There's also a filter called Flash, which appears to lighten and smooth skin.

FaceApp's Saint Petersburg-based creators claim it will "transform your face using Artificial Intelligence", allowing selfie-takers to alter their photos to look old or "beautify" themselves.

“We developed a new technology that uses neural networks to modify a face on any photo while keeping it photorealistic,” said FaceApp founder and CEO Yaroslav Goncharov. “After applying a filter, it is still your photo. Other apps intentionally change a picture in a way that is entertaining, but not a real photo anymore.”

The fun app has already gone viral and is attracting more than 100,000 new users every day.

FaceApp is available on iOS and Android and is free to download from the Apple App Store and Google Play Store.

HOW DOES IT WORK?

Users can edit existing photos or take brand new ones using their smartphone.

Using algorithms, the app transforms photos in a matter of seconds.

As well as making people look younger, older and of a different gender, the app also allows users to modify their photos by adding smiles.