This app is for people who needs to know how old something is. It could sound like a small and insignificant problem. But if for instance if you have a small child then you will get asked a lot for the age of the kid. Imagine then to have the answer, in years, months and days, directly among your today screen widgets! You dont even have to start the app to check! Or you can check on your Apple Watch, its that simple!
It doesnt have to be kids it could be cats, dogs, horses, iPhones, TVs, MacBooks. Anything!