In a recent class , I was learning how to draw a free body diagram of an object. In the first illustration my teacher taught how to draw a free body diagram of block resting on a horizontal surface. He said that earth is pulling block towards itself with a force equal to it's weight, therefore block has tendency to go vertically downwards and block pushes surface due to that tendency and in return surface pushes block by normal force.
I was confused by the point that surface pushes block by a normal reaction force because block pushes it with a force equal to it's weight or because block pushes it by contact forces electromagnetically. I think surface exert normal force on block because also exert normal force on surface ( contact forces ) and not because block pushes it with it's weight.