Answer:
Hard to catch, easy to hold. Can't be seen, unless it's cold
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.
Black we are and much admired. Many seek us if they are tired. We tire the horse, and comfort man, and turn White when we've fulfilled your plan.
So cold, damp and dark this place. To stay you would refrain, yet those who occupy this place do never complain.
I am so simple that I can only point. Yet I guide men all over the world.
You use it between your head and your toes, the more it works the thinner it grows.
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?