The APP allows putting a name to the photo file, it helps to know what is or event, such pudes put the "Vacaciones2016" prefix to your photos, so when you download them to your you can to PC identify them easily, your photos they will be named as "Vacaciones2016-1.jpg", "Vacaciones2016-2.jpg", etc.
It is also useful for service companies where you can prepend the client code that antiede for example "12345678" and the photos will be released named as 12345678-1.jpg, 12345678-2.jpg, etc.