While I'm a challenge for one and a rebuke between two, Yet I still have a direction for every number. What am I?

Answer: Crosswords

More What am I ? with answers

More What am I ?

White, dark, round, square, big or small, I am seen on Valentine’s Day, and loved by all. What am I?
Whoever made me don’t want me. Whoever bought me don’t need me. Whoever use me don’t know me. What am I?
Whoever makes it, tells it not. Whoever takes it, knows it not. Whoever knows it, wants it not. What am I?
Whoever makes me, tells me not. Whoever takes me, knows me not. Whoever knows me, wants me not. What am I?
With a halo of water and a tongue of wood, stone as skin long I stood. What am I?
With me you are blind, To others and what they are, Over me you cannot see, Even though I'm in your head, I am full of myself, I think I'm better than you, I'm a horrible thing to be, Can you tell me, What am I?
With no hammer or any kind of tool I build my house so quickly. What am I?
With the rich I am blue, with the poor I am red, with the amphibian I am cold but with the dog I am hot instead, What am I?
With three eyes and a black as night, I frequently knock down ten men with a single strike! What am I?
Without a bridle, or a saddle, across a thing I ride astraddle. And those I ride, by help of me, though almost blind, are made to see. What am I?
Without feather or wing I fly, but you'll known what I am when I hover near by. What am I?
Without me where would you be? I am not your eyes, but I help you see. What am I?