Answer:
u always follow me but I am rarely seen
What word when read from left to right is a ruler, but when read from right to left is a servant?
Weight in my belly, trees on my back, nails in my ribs, feet I do lack. What am I?
I am just two and two. I am hot. I am cold. I am the parent of numbers that cannot be told. I am a gift beyond measure, a matter of course. What am I?
I'm sometimes white but most often I'm black. I take you there but never bring you back.
Whoever made me don't want me. Whoever bought me don't need me. Whoever use me don't know me.