Water

Water is a compound essential for all forms of life known to date in the earth, but not on another planet. Water covers nearly 71% of the earth's surface. Water mostly found in the ocean (salt water) and the layers of ice, but can also present as clouds, rain, rivers, fresh water, lakes, water vapor, and sea ice.

The water in these objects move follows a cycle of water, namely: through evaporation, rain, and the flow of water over the soil surface (runoff, including springs, rivers, and estuaries) to the sea. Clean water is essential for human life.

In many places in the world there is a shortage of water supply. Water resources management that are less well able to cause water shortages, monopolization and privatization, and even fuel the conflict.

Water is a chemical substance with chemical formula H2O: one molecule of water consists of two hydrogen atoms covalently bonded to one oxygen atom. Water is colorless, tasteless and odorless at standard conditions.

Water is often referred to as the universal solvent because water dissolves many chemicals. Water is in dynamic equilibrium between liquid and solid phases under standard temperature and pressure. In the form of ions, water can be described as a hydrogen ion (H +) that associate (bind) with a hydroxide ion (OH-).