What is Water

Water is a colourless, tasteless, and odourless substance that is essential to all forms of life that we know of.
There is a lot of water on our planet, and it exists in many places and forms: mostly in oceans and polar ice caps, but also as clouds, rain water, rivers or freshwaters. Water is continuously moving through the cycle of evaporation, precipitation, and runoff, back to the sea.
All known forms of life need water. Humans consume "drinking water" - water which has qualities compatible with the human body. Ordinary rain water in many countries is polluted and therefore not safe to drink. This natural resource has become scarce with the growing world population, and its availability is a major social and economic concern.
Water is one of the most common substances on the Earth. Covering over 70% of the surface of the Earth, it is easy to find. Even in a desert, it is not hard to find water, if you know where to look.
Scientists believe that the amount of water on Earth does not change appreciatively over time. In other words, the amount of water that is on the Earth today, is the same amount that was on the Earth during the reign of the dinosaurs.

Why is water so important to life? It all has to do with the unique properties that water exhibits. Firstly, it is the only substance on Earth that is in liquid form at the temperatures commonly found on the Surface of our planet. Secondly, it is a superb solvent, meaning that other substances regularly and easily dissolve into it. This allows water to carry nutrients to cells, and carry waste away from them.

In addition, water has the unique property of expanding as it freezes. Because water expands becoming less dense, frozen water, or ice floats. This is very important, because it protects the water underneath, insolating it from freezing.

Imagine what would happen if water became more dense? It would sink, allowing another layer of water to freeze. Eventually all the water across the entire surface of our planet would freeze, making life impossible.

Rivers and the seas offered opportunity for travel and commerce. Through erosion, runoffs played a major part in shaping our environment providing river valleys and deltas which provide rich soil and level ground for the establishment of population centers.

Water also infiltrates the ground and goes into aquifers. This groundwater later flows back to the surface via springs, or more spectacularly via hot springs and geysers. Groundwater is also extracted artificially from wells.Because water can contain many different substances, it can taste or smell very differently. In fact, we have developed a way to evaluate the drinkability of water: we avoid the salty seas and the putrid swamps, and we like the fresh pure water of a mountain spring.

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