water	groundwater	remaining
dissolved	come over	70%
clouds	evaporates	heats
affected	solar system	droplets

The water cycle (hydrologic cycle) is the path that water takes from earth to the air and back again.

The sun's radiation energy evaporates water of oceans and lakes. The evaporated water condenses and makes droplets in the clouds. Precipitations (rain, snow, drizzle,) start when these clouds come over a cool land area and water backs to the earth. Some of the precipitation changes into underground water which is called groundwater. But most of the water returns to the sea eventually.

Water of rivers takes salts mineral with itself and the salt remains dissolved in the ocean because it does not evaporate. So the remaining water gets saltier and saltier.

Earth's water supply is provided by oceans and oceans cover 70% of earth's surface. No other planet in the solar system has liquid water. The seas and the oceans are the home of the first animals and they are their home at present also. Weather and temperature of earth is affected by oceans. The oceans absorb incoming radiation of sun and the ocean currents distributing this energy around the earth. This energy heats the earth and air during winter and cools it during summer.