Did you ever think about how you look like if you are a female ? maybe a male?
Do you want to see now how you look after 20/25/30/..etc?
Do you want to see how you look with long hair? short hair? black hair? brown hair?
How it looks if you have a different eye color from what you have now? Brown eyes? Blue eyes maybe?
Download FaceApp
Not only the age, but the app is also having other pretty surprising features which we think most of the time about our physic/appearance.