This chapter deals with everything related to hydrogen, including its action on litmus, combustibility, its action with different substances like oxygen, chlorine gas, metallic oxide, and finally its uses and tests. 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. Water helps to regulate body temperature. Freshwater is necessary for the survival of all living organisms on Earth. Our bodies are made up of about 60% water, and we cannot survive more than a few days without it. Water is a precious substance that meets our physical needs while at the same time being of great spiritual importance to many people.