mothers

I define useful as the following:

You encounter a random person on the street and they ask what it's good for. They say you can say anything as long as it is not entertainment related and benefits them directly in some way.

The purpose of the above situation is to show that application cannot be specific to a given socioeconomic status, career, job, gender, etc. It must be something that's useful to more or less anyone in the planet, even if they don't have internet.