Without it, the biosphere that exists on the surface of the earth wouldn't be possible. To understand, we need to turn to the Hydrologic Cycle . Water's molecular arrangement is very simple, two hydrogens to each oxygen atoms, but this is misleading.
Water has many unique properties that allow it to be such a universal material.
One special characteristic of water is its ability to change state very easily under Earth conditions. It can be found readily on the planet in all of its three forms, solid, liquid, and gas. These forms also play a great part in the hydrologic cycle. The hydrologic cycle takes place in the hydrosphere ,this is the region containing all the water in the atmosphere and on the surface of the earth. The cycle is the movement of water through this hydrosphere.