Question

Why does a cloud not fall down from the sky to the earth like any other object that does fall down due to gravitational force of the earth??

Answer 1

Because the density of could is less than air that's why.

Answer 2

So, even though typical clouds do contain a lot of water, this water is spread out for miles in the form of tiny water droplets or crystals, which are so small that the effect of gravity on them is negligible. Thus, clouds seem to float in the sky.