Water – chemical without color and a smell with quite simple formula of H2O. Meanwhile, it is difficult to overestimate its value in life of each individual in particular and all planet in general.
First of all it is necessary to tell about a water role on our planet. Water at Earth is present at three aggregate states at once: liquid, firm and gaseous. Liquid water in the form of oceans, the seas of the rivers and lakes covers about 70% of the earth's surface, in the most active way participating in formation of a land relief, climate and weather on all planet. Water vapor is a part of the terrestrial atmosphere, and ice covers, are presented by a bigger part in two regions: To the Arctic and Antarctic (though not only there). Water is irreplaceable substance on the planet, in water, in the standard opinion, life arose. The biological role of water is big, it is the substance defining a possibility of existence of all living beings on Earth, playing a role of universal solvent in which there are main biochemical processes of living organisms. Water rather well dissolves both organic, and inorganic substances, providing the high speed of course of chemical reactions in cages. Water remains liquid in quite wide temperature range, and in that which is widely presented on the planet Earth now. Covering a significant area of a surface of the planet, water is the native habitat for hundreds of thousands of species. Without water all live on the earth will die at once. The human body contains from 55% to 78% of water, depending on the weight and age, and loss by a human body can lead more than 10% of water to a lethal outcome. The person needs to use about 3 liters of water a day. As it was already told above, water is solvent for many substances in this connection, it is used as industrial solvent and also for cleaning of objects of human activity. Besides, water as the heat carrier is used in thermal networks and nuclear power, and in some reactors it is used also as the delay mechanism of neurons that provides effective course of chain nuclear reaction. Water is actively applied in fire extinguishing, agriculture, also as lubricant (to lubricant of bearings from wood, plastics, etc.) and the tool for splitting, loosening and cutting of breeds and materials.