Answer:
What grows in winter, dies in summer, and grows roots upward?
Being able to interpret the letters on this screen proves that you have this quality.
Who makes it, has no need of it. Who buys it, has no use for it. Who uses it can neither see nor feel it. What is it?
Sleeping during the day, I hide away. Watchful through the night, I open at dawn's light. But only for the briefest time, do I shine. And then I hide away. And sleep through the day.
There is a puzzle which can be asked all day with a different correct answer each time. What is the puzzle?
What never gets any wetter no matter how hard it rains?