Wikipedia –excerpts
The Earth is often referred to as the BLUE PLANET because when viewed from space it appears blue. This blue color is caused from the reflection of oceans which covers roughly 70% of the area of Earth.

Water can be found in three states: liquid, solid (ice), and (invisible) water vapor in the air. Clouds are condensed accumulations of water droplets.
Water is a chemical substance with the chemical formula H2O. Its molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water also exists in a liquid crystal state near hydrophilic surfaces.
Water covers 70.9% of the Earth's surface and is vital for all known forms of life.
It is found mostly in oceans and other large water bodies. Water on Earth moves continually through a cycle of evaporation or transpiration, precipitation, and runoff, usually reaching the sea.

Clean drinking water is essential to humans and other lifeforms. Some observers estimated that by 2025 more than half of the world population will be facing water-based vulnerability.

A recent report (November 2009) suggests that by 2030, in some developing regions of the world, water demand will exceed supply by 50%.
The major chemical and physical properties of water are:

Water is a liquid at standard temperature and pressure. It is tasteless and odorless. The intrinsic color of water and ice is a very slight blue hue, although both appear colorless in small quantities. Water vapor is essentially invisible as a gas.

• Water is transparent in the visible electromagnetic spectrum. Thus aquatic plants can live in water because sunlight can reach them. Ultra-violet and infrared light is strongly absorbed.

• Water is a good solvent and is often referred to as the universal solvent. The boiling point of water (and all other liquids) is dependent on the barometric pressure. For example, on the top of Mt. Everest water boils at 68 °C (154 °F), compared to 100 °C (212 °F) at sea level.

Taste and odor- Water can dissolve different substances, giving varying tastes and odors. The taste of spring and mineral water, are derived from the minerals dissolved in it. Pure H2O is tasteless and odorless. Pure mineral water is in the absence of toxins, pollutants and microbes.

Distribution in nature
In the universe- Much of the universe's water is produced as a byproduct of star formation. When stars are born, their birth is accompanied by a strong outward wind of gas and dust. When this outflow of material eventually impacts the surrounding gas, the shock waves that are created compress and heat the gas. Water is quickly produced in this warm dense gas
Water has been detected in interstellar clouds within our galaxy, the Milky Way..
Water and habitable zone-Hydrology is the study of the movement, distribution and quality of water throughout the Earth. Other specific studies on water carries different names.

The water cycle ( hydrologic cycle) refers to the continuous exchange of water within the hydrosphere, between the atmosphere, soil water, surface water, groundwater, and plants.

evaporation from oceans and other water bodies into the air and transpiration from land plants and animals into air.
precipitation, from water vapor condensing from the air and falling to earth or ocean.
runoff from the land usually reaching the sea

Drinking water-The Institute of Medicine- recommended that, on average, women consume 2.2 liters and men 3.0 liters—this is recommended to be 2.4 liters (10 cups) for pregnant women and 3 liters (12 cups) for breastfeeding women.

Water for bathing may be maintained in satisfactory microbiological condition using chemical disinfectants such as chlorine or ozone or by ultraviolet light. The single largest (volume)of freshwater resource suitable for drinking is Lake Baikal in Siberia.

Chemical uses- Water is used in chemical reactions as a solvent or reactant, as a solute or catalyst. Water has a high heat of vaporization makes a good fire extinguishing fluid. In the nuclear power industry, water can is used as a neutron moderator. In most nuclear reactors, water is both a coolant and a moderator.

In Food science, water activity affects many chemical reactions and the growth of microbes in food. Water hardness is also a critical factor in food processing. Boiling, steaming, and simmering are popular cooking methods.

Water Politics is politics affected by water and water resources.
Water used in the production of a good or service is virtual water.
A 2006 United Nations report stated that "there is enough water for everyone", but that access to it is hampered by mismanagement and corruption.
The UN World Water Development Report (WWDR, 2003) from the World Water Assessment Program indicates that, in the next 20 years, the quantity of water is predicted to decrease by 30%. 40%. The world's. Ramsar Convention. World Day for Water takes place on 22 March and World Ocean Day on 8 June.