Water is an inorganic, transparent, tasteless, odourless, and nearly colourless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms. It is vital for all known forms of life, even though it provides no calories or organic nutrients. Water is a substance composed of the chemical elements hydrogen and oxygen and existing in gaseous, liquid, and solid states. It is one of the most plentiful and essential compounds. A tasteless and odourless liquid at room temperature, it has the critical ability to dissolve many other substances. Water carries nutrients to all cells in our body and oxygen to our brain. Water allows the body to absorb and assimilate minerals, vitamins, amino acids, glucose and other substances. Water flushes out toxins, and waste and Water helps to regulate body temperature. Water is an essential chapter as it involves basic concepts students require in all their future studies. This Selina Solution provides you with the knowledge about Water as a solvent, solutions, mixtures, effect of temperature, pressure on solubility, hydrated and anhydrous substances, crystallisation of Water, properties of water, drying and dehydrating agents, soft and hard water.